At first I thought maybe the users i was attempting to block were mods or admins or something because i keep getting a message "unable to block xxxxxx" then i tried using another app without issue.
Any reason why mlem does not allow user blocking? I had tried on both my ipad and my iphone.
Looks like a bug. Initial testing suggests that you can block users from comments, but not from posts right now. Nice find, thanks for letting us know! Should be fixed tomorrow.