I was having this issue on my communities on lemm.ee. I was able to correct it by setting the community language to undetermined from a browser.
If you aren’t the mod of the community you might try reaching out to the mods and ask them to maybe open up their community language so Memmy users will be able to post.
If you still have enough of an interest that you might start collecting again I wouldn’t sell.
It will be hard and even more expensive to rebuild a second time.