There is an issue currently under investigation where roblox will sometimes incorrectly remove cached sound files on process close (even if another studio process still needs the cached file). This sounds related, I’ll ping the engineer working on the fix and ask them to update this thread when we have pinned the issue down / have a fix going out.
We enabled a fix for this issue (it should be the same issue as described here: Audio doesn't play - #11 by mrdooz) earlier this week. Please let me now if you’re still having issues.