older email not appearing in client

older email not appearing in client

Hello Zoho community - looking for some guidance on the following.

Email going back to 2016 and later is not showing up in my email client (Outlook or Thunderbird) - if i log into the web and access my mailbox all my email is present. 

My configuration is:
Outlook 2016 client 
Configured with ActiveSync

thanks
-Z