iPhone/iPad Mail: "Unable to Move Message" Error

iPhone/iPad Mail: "Unable to Move Message" Error

Since Thursday, Dec 22 I have been unable to delete messages from my Zoho mail account using my iPhone or iPad.  An unread message that I mark for Delete only becomes "read," but it won't move to the trash.  I get an iOS blue alert that says "Unable to Move Message," and the OK button.   I did not change anything on either device.  Occasionally a random delete attempt does work, but it is a 1 in 10 chance right now.  I have tried moving things to other custom folders as well, same issue.   I normally do mass deletes of all messages at the end of the day and that has always worked.  Whether I try to delete 100 emails or just one, I get this same error.

Is there anything on the Zoho Mail side that has changed in the IMAP behaviors for moving messages?

Any thoughts on this issue would be appreciated.  Currently, I have to log into Zoho Mail from a web browser to move emails.  I have already deleted my Zoho account on my iPhone and recreated it, same issues.  I have already assigned the iPhone trash command to move messages to a different folder, same issues.    Thanks.