Issue with Outlook for Mac

Issue with Outlook for Mac

The last few days I experienced problems by using Outlook for Mac (Office 365` for Mac). First of all I'm not able to find almost half of my incoming messages to my Inbox folder while I'm sending outgoing messages I cannot find it in the Sent folder! At the same time when I'm using the Zoho front end everything is ok and I have 100% visibility of my incoming and outgoing messages. 

Another issue is that every almost half hour the system prompts an authorisation message and calls to enter again my password. Till then I 'm loosing the connection with Zoho Server.

I searched for any updates or patches but I didn't find anything.

Any help is more than welcome.