Acrobat PRO or Acrobat web unable sync, post and lost comments

We have a Creative Cloud Teams sub, and use the Acrobat online shared reviews extensively for PDF documents with SMEs.  But we are now seeing more and more errors or problems related to these shared reviews.

We share documents almost daily and it is not all documents that appear to have problems.  But the problems are becoming more frequent.  And reviews that have been running successfully online for a while, may suddenly start having problems.

These problems include:

• Unable to post comments or replies either with desktop app or web online
  • Message given : "We were unable to post your comment. Please try again."
  • or "Error syncing comments. Please try closing and reopening this file."
  • Waiting (even for days) or trying again doesn't seem to resolve it.
  • Oddly this problem can appear after many comments have already been posted successfully, but once it starts reporting the sync issue, it seems that the review can no longer by commented on.  
• After sharing a PDF directly with Acrobat PRO, sometimes it fails to upload and becomes stuck in the "Shared by you" list.  Trying to access it only gives a message "It is not available at this time".
  • I found I can remove these "corrupted" uploads from the online document reposistory, so at least it is no longer listed under "Shared by you".  
• Sometimes whole words posted with the online Acrobat get posted as individual letters, so as the review types each letter is added as comment.
  • I have the email notifications set on, and can see this happen.
  • I've had several different reviewers encounter this problem.
• Some reviewers have made comments, where I have seen the email notification, but where the comment has disappeared completely.  They did not delete it, it just disappeared.  

Example problem:

I have a review that was uploaded and shared on 4th September successfully, with 94 comments added.  Today, 20th September, I tried to add an additional comment and got the error syncing.  I asked a colleague to see if they could post to the review online, but they also get the error.  So it now appears this review isn't working anymore. 

Not always do the SMEs inform us they see an error either, so we don't always know that there is a problem.  And our SMEs are beginning to lose faith in this review process.

I've checked I'm running the latest Acrobat PRO DC version when sharing these.  But my guess this is a cloud problem.

Any help would be appreciated.