I first notice maybe a week or so ago that emails coming to my account are not syncing across my iPhone and the Zoho web client. I've used Zoho on my iPhone for years and this is new with no settings changed by me. An example of the issue. Email read, possibly deleted or moved to a different folder from iPhone (12 Pro Max running 14.7.1). The email remains in the unread state in the Inbox in Zoho. Emails received Friday and over the weekend and deleted, moved, read, etc are still in the Inbox in Zoho Monday morning. 

I only use this for personal use for a domain I own to have a personalized email account. I haven't updating anything in the settings on the iPhone or in Zoho. Again, I access the mail client through the web (mail.zoho.com). Any ideas what could be causing the issue or how to resolve it?