Unable to post in the Discord Cabin Shell Challenge

I'm trying to post my entry in the Discord Cabin Shell challenge, but whenever I try to add my entry, Discord says it's processing, then a second later the whole thing disappears and it's as if I never posted. I tried again later with the ethernet cable connected, and I tried reducing my images to 1080p resolution down from 1440p. I've tried with the app instead of through my browser, but it's the same result. I tried posting with my tablet, but I couldn't upload the pictures at all and the android version of discord has been having problems that aren't on the computer version. I reported the problem to Discord, but there's been no response. I searched the issue on google, but I can't find anything on it. It's very frustrating because I want to enter, but Discord refuses to post my message and I've tried all I know. Does anyone know what else I can do? Does Discord have some max message size limit they don't tell us? I'm on the free Discord account on Windows 11 using Google Chrome browser.