@Sam0054 

Sorry for the late response. I never saw a notification that there was a reply. 

I setup a pool with latest versions of DEM and Horizon View Agent. Also installed latest Horizon client on desktop and rebooted our DEM server. Logged in with an account that was having the issue and it wasn't resolved. 

I blew away the DEM profile. Logged in to create a fresh new profile and was prompted to allow drive sharing as expected. I clicked allow and left the "Do not ask me again" option unchecked. 

I logged off of that account and then back in a few minutes later. No prompt to allow drive share and no network drive showing the drive redirection. It seems like once it gets to this point there's no way to get the drive redirection to work again without deleting the DEM profile. 

Update: I've found a way to recreate the problem. I just don't know how to fix it. As soon as my O365 credentials are being synced to Edge within the VDI session it will not map the drive share. When I sign out of Edge and log off and back on the drive share works.

I thought maybe roaming the Edge settings was causing the drive share to timeout or something. So I found the GPO for View Agent Configuration/Horizon Client drive Redirection and set the timeout from the default 5 seconds to 20 seconds. But that doesn't seem to be making a difference.