Hi Anas,
Based on your description, the issue only happens in one Outlook Client rather than OWA or other Outlook Client, it means it should be an Outlook Client issue.
Considering you have tried the safe mode, repair and reinstall, I suggest you add another account which works fine with the affected Outlook Client to narrow down the issue. If the issue continues, please try 32-bit Outlook Client (if you are using 64-bit) Outlook Client. If the issue is not resolved, since our forum focuses on Office 365 online, I suggest you turn to our dedicated Outlook forum (https://social.technet.microsoft.com/Forums/office/en-US/home?forum=outlook) for further assistance. Your understanding is pretty appreciated.
Thanks,
Jessica Zhang