outlook 365 won't open since upgrading to OS Catalina 10.15.5

Hi, does anyone have a solution for outlook 365 refusing to open after upgrading to Catalina 10.15.5?

So far have tried the following without success:

• Created new default outlook profile - no change, existing profile not corrupted
• Moved plist files to bin - no change, still wouldn't open
• Checked font manager - no new font manager since April this year so not the cause
• Created new Mac profile, installed autoupdater again and ran updates, still wouldn't open
• Deleted any MS Office or Outlook keychains - still wouldn't open
• 2.5hrs online with Microsoft support who then said they couldn't resolve

All other MS Office programs up to date and working fine.

All. help much appreciated. Thank you