Early this year, Joanne Brakatselos, a rock fan in Queens, spent just over $1,000 for tickets to six concerts. In the months since those events were canceled because of the coronavirus, she got her money back for every show.

Except one.

Ms. Brakatselos is one of the thousands of fans still awaiting refunds for Tool and Judas Priest shows at the Nassau Coliseum on Long Island, a case that has begun to draw attention and finger-pointing behind the scenes of the music industry.

For consumers like Ms. Brakatselos, who paid $356.70 for two tickets to see Tool, getting those refunds has been an exercise in frustration. Since June, when the band’s show was canceled, she has been back and forth numerous times between Ticketmaster and the Coliseum, to no avail.

The venue box office repeatedly asked for her patience and said it was working on the problem, while Ticketmaster said it was awaiting funds from the “event organizer,” according to emails and other communications Ms. Brakatselos shared with The New York Times.

“Both sides are pointing to each other, and I’m monkey in the middle,” Ms. Brakatselos said in an interview.

But Nassau County, which owns the Coliseum, says responsibility for the refunds rests with the former leaseholder of the venue — a company run by the billionaire Russian investor Mikhail Prokhorov.

“Under the county’s lease agreement, resolving refunds falls squarely with the tenant,” a spokeswoman for the Nassau County Executive, Laura Curran, said in statement. The county directed further questions to Mr. Prokhorov’s company, Onexim Sports and Entertainment, which held the lease on the arena until August, when a deal brokered by Nassau County transferred it to an investor that had financed recent renovations to the 48-year-old building.

(As part of that deal, the investor, U.S. Immigration Fund — which is not affiliated with the federal government — paid more than $2 million that Onexim owed the county in back rent.)

The reason for the delay of the refunds remains unclear, as is the question of how the problem will be resolved now that Mr. Prokhorov’s company is no longer in control of the venue.

Nassau Events Center, the Onexim subsidiary that operated the venue, said it is “working closely with Ticketmaster regarding refunds for tickets purchased through that channel, and is aiming for those refunds to be processed as soon as possible.”

The company noted that fans who bought tickets directly from the Coliseum box office — usually a tiny portion of overall sales — can get their money back from the venue. But it did not respond when asked about the cause of the delay in refunds through Ticketmaster, or whether it could offer any more specific timing.

Mr. Prokhorov, who made his fortune in metals through the privatization of former Soviet assets in the 1990s, is well known to sports fans as the former owner of Barclays Center and the Brooklyn Nets. He is worth $11.3 billion, according to Forbes, and most recently has invested in virtual reality.

Ticketmaster’s exposure to refund claims is also uncertain. The company tells its customers that it pays refunds for all canceled shows in about 30 days. But the coronavirus shutdown has dealt a severe economic blow to Ticketmaster and its corporate parent, Live Nation Entertainment; the company reported that its revenue for the second quarter this year dropped 98 percent from the same period in 2019.

In a statement, Ticketmaster said only that it is “currently waiting” for Nassau Events Center to transfer the ticketing funds “so we can pass refunds along to fans.”

In addition to the canceled shows by Tool and Judas Priest, several other events that were on the arena’s calendar this year, including by Elton John and Michael Bublé, have been rescheduled for 2021 and 2022. Under Ticketmaster’s typical business arrangements, the ticketing money from those shows also would have been forwarded to Mr. Prokhorov’s company.

The New York Islanders, the National Hockey League team long associated with the Coliseum, canceled six home games because of the pandemic, and, according to information from the team, refunds for those tickets were paid to fans.

In the spring, as all tours came off the road, the prospect of billions of dollars in potential ticket refunds became a hot-button issue for the concert industry, and a rallying point for frustrated fans. But by May, much of that problem had seemingly been resolved, when Live Nation and AEG, the two corporations that dominate touring, announced refund policies.

In August, Live Nation said it had processed $695 million in refunds through June, and was expecting to pay $270 million more in coming months. About two-thirds of that total, the company said, is for events put on by Live Nation itself. (Ticketmaster also sells tickets on behalf of thousands of other clients.)

But the global touring market, which is estimated at more than $20 billion, includes far more players than just Live Nation and AEG, and fan complaints about missing refunds or unresponsive venues dot social media.

The Nassau Coliseum, however, is an especially high-profile case. Opened in 1972, it has long been part of the mainstream concert circuit, including a close association with Billy Joel.

John Scher, the veteran New York-area concert promoter who was putting on the Tool show, said he has been flabbergasted by the arena’s refund failure. In an interview, Mr. Scher said that his contacts at Ticketmaster and the venue told him that Ticketmaster had forwarded the money from the concert’s ticket sales — a little over $1 million, he said — to the Coliseum’s operators.

Mr. Scher said he had been unable to get answers about who was holding those funds and when refunds would be paid. But he minced no words in blaming Mr. Prokhorov and his company for the problem.

“The fact that they’re not refunding the money is blatantly unfair to the ticket holder,” Mr. Scher said in an interview. “There isn’t any gray area. He ran the building and took in the money.”

A spokeswoman for Mr. Prokhorov declined to comment beyond the statement issued by Nassau Events Center.

In a statement, Tool said it had not received any money from the show, and that “we simply do not have enough information to comment on the situation.”

But the band Judas Priest, which canceled a September show at the Coliseum, was more pointed.

“We hate the thought that fans are not getting their refunds but unfortunately we have no control over it,” said Jayne Andrews, a manager for the band. “The issue doesn’t lie with us, Live Nation or even Ticketmaster — the building must return the money to Ticketmaster first in order for Ticketmaster to do the refunds.”

Ms. Andrews said Judas Priest has had no refund problems at any of the other venues where it has canceled shows.

When Tool announced in June that it was not going forward with its tour, the band made a point of saying that it was canceling its dates, rather than postponing them, so that fans could get their money back. “In our opinion, tying up our fans’ money for months, if not a full year, is unfair,” the band said.

That resonated with fans like Ms. Brakatselos, who said she has spent considerable time over the last four months hunting down the money she was owed — a quest that, for her, has involved setting up a spreadsheet to track her many communications with Ticketmaster and the Nassau Coliseum.

“This is almost $400,” she said. “This is not something I can just let go.”