I've got one post scheduled every day to post in lotrmemes@midwest.social for the account https://lemm.ee/u/Wikischedule, but as you can see from the account linked, it misses quite a few days at a time, and has missed the last 5 days in a row.
Let me know if there's any more info I can provide about the issue ~
so I had a similar issue and I think it's to do with how Lemmy Schedule and or the Lemmy instance is handling image uploads. in general I've had issue uploading images to my Lemmy instance, so pointing to a URL has seemed to work out better for me. I've been using freeimage.host. In addition I've spun up my own copy of Lemmy Schedule using docker instead of using https://schedule.lemmings.world, so it could be one of the two.
Looked through the logs and I get the error 413 there, which means the image is too large for the target server, so @hoover900@sh.itjust.works was right, you should probably upload it somewhere else first and then link it. Or ask the admins if they'd consider increasing the size constraints.