Outlook window resize issue

I am facing a very unique issue. Say, out of 10 times when I start MS Outlook, 8 times it opens in the size as shown below .

Things that I have tried

1. I already tried the method of resizing the window by right clicking the title menu, choosing size, then using the keyboard arrow keys to make the right size. But that did not help.
2. I also used the mouse to resize and then close it but that did not help.
3. I maximized the window and then close the application but that also did not help.

I finally wrote a vb.net application which deletes the registry key named Frame in the below location.

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Office Explorer

The above works but I am now tired of deleting the key everytime. Even after deleting the key, it is recreated in sometime. I recently re-installed Windows and MS Office but the problem did not go away.

Any idea how can I get this sorted permanently?

Note: I have researched Google for this and the closest that I have come across is THIS post. But it did not solve my issue.

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