I hope others find the following helpful. I ran some tests on my work laptop running Windows 10 Pro.
The application tested in PiP has been proven to work without PiP and is already in active service. Therefore the argument that something might be wrong with the application lacks merit.
Test 1 - Change Open Browser Activity Setting UserDataFolderMode > to Default
Browser Window refuses to open as a result of the following Error Message:
Open in Chrome: The browser already runs in the main session. Please stop the browser or set another user data directory and restart the automation in PIP.
The workaround to this problem in Attended Automations might be that the human user has to work with a Browser that is different from Chrome. If that does not work , and if the human user has to stop working to make way for the Robot, then that defeats the very purpose of having PiP.
The other option is Test 2.
FYI: I enjoyed working with this feature in the 2019 version. The Robot ran alongside in PiP mode without interrupting my work. I miss that very much now.
Test 2 - Change Open Browser Activity Setting UserDataFolderMode > to Automatic
Browser Window Opens but subsequent steps fail as a result of this Error
System error at initialization: Cannot communicate with the browser, please check the UiPath extension. at Source: Invoke SF_Open_Chrome workflow: Open in Chrome
This is because the PiP Browser profile folder is being created for the first time and we have to enable the Chrome Browser Plugin for the first time inside of the PiP window.
Restarting the application will go past this error, but will fail on the Click Activity
Reason: SimulateClick in the application was set to True. After I switched it to Blank, the process worked inside of PiP.
Strangely, SimulateType works but not SimulateClick! 
The next options was to set SendWindowsMessages to True and setting SimulateClick to Blank - And this worked in PiP
Test 3 - Purely Accidental - VPN Connectivity Fails when PiP Window is Open
I lost Wi-Fi connection midway during the test and when I got it back, Cisco VPN failed to reconnect complaining that a connection from a Remote Desktop Window cannot be established.
I was able to connect successfully once I closed the PiP Desktop.