It does indeed seem to have been an issue with loading metadata for the image at the time.
I'm not sure if sdf pict-rs was slow at the time or what was causing it at this point, but Lemmy cut it off after 9 seconds of processing the post and that's where it failed. Unfortunately the logs don't give a reason currently.
If you remove your vote on the post and restore it after a minute it will likely trigger it to get processed properly, although this is obviously not a usable solution.
We'll have to look into if we can improve this somehow.