An update for my issue.
The issue suddenly got a lot worse around a month ago. In the last few weeks it got so bad that the left speaker basically never works, and plugging it in to charge would cause both speakers to stop working.
When I finally had some free time I went to open the machine again to inspect the audio card, but upon flipping the machine over to undo the screws I found this:
Not the clearest picture, but if you look at the bottom left corner of the silver expansion card you’ll see a 4-5cm long crack spreading towards the middle of the case.
There is an ongoing issue reported in August 2025 for FW12’s which have their bottom case cracking: [TRACKING] FW12 cracking issue
I believe this was the actual cause of the audio card issue, so I wanted to include an update here in case it clues other folks in to cracking issues with their own cases. Not sure if it’s the actual cause for the seemingly related issue from others in this thread, but worth checking on.
I’ve opened a support request to get a new bottom case, once I have it swapped I’ll update here as to whether I have any more audio issues.