Comments unavailable. Answered
When I try and make comments, or reply to comments, the comments box doesn't appear.
Instead, I get a faint grey 503 message, and the processing icon overlaying it and not stopping for several minutes (at which point I get bored and hit the back button).
(And while I tried to post a screen-shot, I twice got the error 504 Gateway Timeout)
Edit: see also https://www.instructables.com/community/New-editor-error-503/