I'm in the middle of reviewing the new Bose Noise Canceling Headphones 700, but before wrapping that up, I felt it was necessary to address an ongoing situation with the company's previous set of headphones. Over the last few weeks, many owners of the Quiet Comfort 35II headphones have been insisting that a recent firmware update has noticeably worsened the level of noise cancellation. Outside noises are now easier to hear, whereas they were mostly hushed and inaudible before the update.

If you want more background, read this extremely long, comprehensive thread at Bose’s customer forums that discusses the issue in detail. “I created an account just to post that the 4.5.2 firmware update has totally destroyed the ANC on my pair of QC35 II too,” one person wrote. “Very disappointed with Bose as I only purchased these headphones in April and they are basically useless to me now on my commute and in the noisy open office.”

There are a lot of these complaints, with some of them claiming that the loss in noise cancellation actually began even earlier with firmware 4.3.6. “This is true happened to me today, auto updated thru bose connect app while I was at Starbucks, and I immediately noticed the degradation in ANC, now I can hear people’s conversations on the other side of the coffee shop, while on high NC setting,” a Reddit user wrote earlier this month.

Not all QC35 II customers are running into the same troubles. “Took a leap of faith and did the update,” another forum poster wrote. “As soon as I completed the update i reset the headphones and all seems to be working fine, ANC included. Will see how things turn up after some days of testing.” One user came up with a fairly complex reset and reinstallation process that seems to have done the trick for their unit and other QC35 II owners as well — but not everyone.

But here’s the thing: Bose says that none of this should be happening and that no customers should be experiencing any loss in noise cancellation effectiveness. A spokesperson told The Verge by email today that the QC35 II product team is “aware of the complaints,” but the company is adamant that it didn’t adjust or alter noise cancellation in any way with the 4.5.2 firmware. “No changes were made to the noise cancellation performance of the QC35II or ANR toggling within the app with the latest software update,” Bose said. “If anyone experiences issues, they’re encouraged to reach out to Bose support.”

Bose discourages customers from downgrading the firmware on their headphones. Last October, an employee wrote “we have seen cases where installing older versions of firmware can create unexpected behavior in a product and negatively impact or reduce functionality. Additionally, downgrading firmware in some cases may not only remove newly added fixes or features, but sometimes security enhancements or other critical bug fixes.”

Nothing leads me to think that QC35 II owners are making this problem up or imagining things. There are enough angry posts to make it pretty apparent that something is going on. Even if it’s not the firmware itself, something in Bose’s update process might be throwing a wrench into NC performance. It’s easy to go all conspiracy and accuse Bose of sabotaging its old headphones so you’ll upgrade to the new ones, but that’s quite frankly silly and would trash the company’s product reputation.

Still, it all makes for a very frustration situation. You’ve got customers swearing up and down that something has gone awry with their pricey headphones, and you’ve got Bose saying there’s no reason that should be the case. I’ll be keeping an eye on this for any subsequent news, and I’d appreciate hearing your own experience in the comments if you use Bose’s QC35 IIs.