Problem with deleting Unread/Read in Outlook

Hi 

I Just finished a migration to 365 and everything was great but for some users they are experiencing a kind of delay in their new outlook profiles. this problem is only with people with big mailboxes 73 GB and 33 GB for example. if they try to delete or mark mail as read or unread it doesn't work unless you close Outlook and open it again.

it worth also mentioning that the user are working on Remote desktop with Office 2019 installed and outlook cach is off through a group policy.