I had previously reinstalled my sound drivers (and they hadn't changed since last year, there were no updates) and it hadn't fixed the issue, but decided to do it again for good measure because I'd done a bunch of other changes since then including bios tweaks and so on (which also hadn't fixed it). I also cleared out all my save files (including some from the previous version that were still hanging around), and lastly, I turned vsync on. I've no idea why or which of these did it, but it appears to have fixed the issue - although I'm living in fear of it rearing its head again now as it's done several times already.
edit: the issue has returned. I'm none of the wiser.
Ever since the 6.1.3 hotfix was released I started having some fairly big sound issues where it cuts out randomly for anything between a split-second and 5-10 seconds at a time.
I posted about this on reddit in some detail (https://www.reddit.com/r/totalwar/comments/1kh6eg0/warhammer_3_sound_cutting_out_since_most_recent/) and thought I'd fixed it but I hadn't. Here's my original post:
"I've been playing the Warhammer trilogy issue-free since 2016 and have racked up thousands of hours across all three games. Since the most recent patch - 6.1.3 - I've started having quite severe sound problems with Warhammer 3 - in battle, campaign, and even on the main menu, the sound has started to cut in and out at random. Sometimes it goes a decent chunk of time before happening, other times it's almost constant. Performance is otherwise unaffected and changing sound settings has no effect on this. I've tried all the solutions suggested when googling other people having similar issues with the game (or games) to no effect.
I've verified my files, I've deleted preferences files in the appdata folder, I've been doing a lot of this at the urging of Sega Support too, since I submitted a ticket to them. No luck so far with any of it. No other games are affected and if I play sound at the same time as the game - a podcast, or youtube video, or just a sound file from my PC - then the background sound plays fine and it's only the game audio that cuts in and out. I've even downloaded Total War Pharaoh again to see if that was affected - it's not, it all works as it should. So I'm pretty confident it's the game itself, especially as it's only started happening since the last hotfix. My next step is to uninstall and re-download Warhammer 3 itself, which I've put off doing because it's such a big download, but I'm not confident that this will fix anything. I don't expect anyone here to have solutions either, although I'm open to anything at this point.
Mainly I wanted to post this to flag up what seems to be a potential (rare) bug - I know that a Troy patch caused sound stuttering issues at one point and that just had to be fixed by CA rather than being something a user could fix on their end. And also to ask if anyone else has been having the same issue? Or am I just the unluckiest sod on earth?"
Since then, as the thread says, I've tried a full redownload of the game, removing Microsoft Teams, forcing a redownload of the Launcher (which fixed performance issues with the Launcher but didn't fix this thing with the sound), reinstalling motherboard drivers, reseating RAM and other components, trying a different graphics card in case it was somehow related, etc. Rolling back to before the 6.1.3 hotfix had no effect either. This remains the only game affected by the issue and background sound does not cut out when the game sound does.