MAC MAIL ISSUE

I have a late 2015 IMac retina SK, 27" running macOS Monterey. My emails are being received but sometimes are not displaying when opened, just the heading, no content. I can see the first few lines of the email in the left pane. If I click on open and then quit MacMail and then reopen, it seems to open that particular email fully, but if I then go to the next email, again I have to quit and reopen. I have as suggested by a previous participant unchecked all items in the privacy box in preferences but this still doesn't work. I would appreciate any ideas as to how I can fix this. Thanks Les