Update: I seem to have fixed the problem although I’m not entirely sure how. I’ll note down everything I did in case it helps anyone else.
I’ve been studying a pretty popular shared deck called Core 2k/6k Optimized Japanese Vocabulary which I first downloaded from this website:
https://ankiweb.net/shared/info/1237389412
In retrospect the problem might’ve been with the source I got the deck from, but back then I didn’t think there would be any problems since it was uploaded on the official Anki web.
This time I downloaded the same deck from another link:
I then imported this deck in both the Ankidroid in my tablet and Anki in my laptop. I synched a bunch of times and then somehow the problem was fixed, at least as far as I can see. The audio in the new cards plays normally and my study progress seems to be the same (at least I hope). I also run Check Media again and this time it showed only 1900 or so files missing, but they were all jpeg files so I don’t really care.
Something else to note, when I tried importing the new deck at first it seemed like it didn’t work. This is the message it displayed on Ankidroid:
I’m pretty sure it said something similar on the computer as well. But I guess it’s all good in the end (fingers crossed).
Thanks for all your help so far!