Can't write comments after trying to respond to Pleroma user

On a different account, I tried to respond to a Pleroma user a few replies into a comment chain. That reply never got accepted by the server, it only shows the loading symbol next to the greyed-out reply button. Since then, I am unable to post any comment or reply on that account. Is that a known bug or what is going on?

Edit: I erroneously thought the user I responded to came from Mastodon. I have changed the title to correct that.

Edit 2: It seems like the request timed out. The comment never appeared, but I can now post again on that account.