Outlook unread numbers not appearing on icon

I have followed all the suggestions made on this forum but am still not getting the numbers of unread emails appearing on the outlook icon, unless I go into the emails and back out again. This was working fine till two weeks ago. I have uninstalled and reinstalled the app, badges is selected etc. I went to an apple store and they couldn’t help either. Please can anyone advise me how to fix this annoying fault? Thank you.