Lemmy.zip converts all images to avoid which boost didn't support. The newest version added support for a if, but it might still be in beta.
Boost for Lemmy
Community of the Android app Boost for Lemmy

They're likely avif files. I hope it's fixed soon, because it's super annoying.
Already fixed in the newest version, and yeah, that was the culprit.
Which version? Still doing it for me on 1.0.29
Weird. 1.0.29 solved the issue for me for the first time since .zip switched to Avif.
See my other comment. I think it's related to the load hq images setting. Can you see if you can replicate it?
I still have the issue with full screen images. It seems that HD images are still not handled correctly.
Ah yeah, if I tap HD, everything is black. Other than that, thumbnails and full images load in 1.0.29.
No issues here. Can you give an example of a post? Tried clearing the app cache?
I can't reproduce it. I'm also on the beta 1.0.29.
Think I figured it out. Can you try going to settings/advanced/media viewer and the enabling load hq images?
Turning it off fixed it for me
Unfortunately it's literally every single image post. Strangely thumbnails load and direct links to posts like this work but if I click on a post on the front page it just loads black.
What version are you on? I think I'm on the latest beta (1.0.29)