Outlook 365 Preparing outlook for first use, Loading mailbox settings

[oryxway]

I have Outlook 365 installed on our Virtual Desktops (VDI) and when I launch Outlook every time it says, 

"Preparing outlook for first use, Loading mailbox settings"

Then starts downloading the mail again

How does this work with the OST file? Does it write to the profile? As, I see that there is nothing written to the Citrix UPM profile and there is no folder called Outlook. The VDIs are Windows 10 and  Outlook 365.

Appreciate any help from experts?

[#2]

@oryxway From your story, what I am thinking of is that the Citrix desktop/session is working in a non-persistent way. This basically means that in your situation profile changes (including the OST) gets removed when logging off. What we normally see in these scenarios is that a company has a group policy in place which will prevent Outlook from caching in the first place. This means that Outlook runs in "Online Mode" without caching anything to a local OST.

Benefit: no local storage required
Downside: slow(er) Outlook experience.

There are however tools which can overcome this issue like FSLogix.