Unable to post in joined Threads on mobile

Hey, so for some reason I've noticed that I've been unable to post in threads that I've joined in on mobile. That the text window says "Channel is read-only". But when I attempt to chat in them on desktop, it works fine.

What's worse is that in terms of server rolls, I have the second highest just below Admin, and that the threads in question are ones that I created. So I have no idea what's happening.