Check your phone with a file manager application. Is there a directory AnkiDroid/general.media/ on the sd-card of the phone with the same set of png-files generated from the latex as there is on the PC?
No, though actually there are other media folders for different decks than the one I wanted to use, which it seems work fine, so I will delete and re-add this deck. Thanks.
Spaced repetition is one of the most efficient ways to learn new things. (For research citations, see 'Study methods', here.)
The best way to practice spaced repetition is to install Anki to your phone, since you have your phone with you all day long.
I have an Android phone, so here's my 60-second guide to getting started with Anki on Android: