Disappearing incoming mail

tmbrophy2003 - Apr 14, 2021 at 11:20 AM
Certain mail from a small number of contacts does not appear in my Inbox, but DOES appear in the Unread mails--until I read it. Then it disappears if I don't move it to another folder. These are from people I know well.
Can anyone help??

System Configuration: Windows / Firefox 87.0