Sometime in the past couple of years photos with % in the filename have stopped being supported in both Ankiweb and AnkiDroid, but still display fine in the Windows desktop version. This is a huge disappointment as I have several decks with hundreds of cards, most of which containing one or more photos with % signs in the filenames which would take a huge amount of work to correct. I have basically stopped using Anki due to this issue alone but am now studying for an exam in which I would really like to work with one of my old decks.
Is there a workaround for this, are the developers aware of the issue?
Okay, I think I already solved the issue! I read a couple other related posts which helped.
My solution on Windows 10 was to use PowerRename (included in PowerToys) to rename any photos in my media collection folder with % and just left the replace field blank. This is easy to do once you install PowerToys, just right-click inside the media folder, choose PowerRename, and go through the find and replace fields.
Similarly in Anki, I used Find and Replace in the Notes menu to remove any % in selected cards. This could get tricky if you have cards where % is needed, though perhaps you could spell it out instead.
I synced everything and all of my cards seem to be working online and on AnkiDroid! Wish I would have worked on this more before.