I suspect this is a bug. Could you send me a copy of your local collection.media.db file after you get the sync error? Please avoid adding/removing any media after that until I’ve had a chance to compare the file you send to AnkiWeb’s end. To get the file to me, you can use something like Google Drive and then send me a link privately via forum message or https://anki.tenderapp.com
As you’ve guessed, creating a new account may resolve the issue like it did for the previous user, so I’d recommend you do that after sending me the file, so you don’t need to wait for me (I won’t be able to look into this until Sun at the earliest). Please keep the old account around though, and let me know when you’ve fully synced the new account, as it will also be useful to compare the records of the old and (presumably working) new account.
Thank you! I messaged you with the file and and the email of the new account. In the new account, I uploaded the same collection+media (exported as colpkg including media and imported into a new profile in Anki, then synced to that new account). When I sync it, I get the “media sync complete” message on the new account. My main (this) account is still stuck on “Please sync again.”
Just in case it might matter, I’m doing my Anki stuff in a separate profile at the moment, because laptop is not really useable for the 5 - 10 minutes it tries to sync and I didn’t want to accidentally keep deleting/adding media. I’ll just export-import it back into this account (or new one if the problem doesn’t go away). So no hurry dae!
For the benefit of others, this was a bug on AnkiWeb’s end, and required me to make a change to Kazue’s account to fix it. If anyone else hits this before I have a chance to address the underlying cause, please reach out and I’ll fix your account for you.