Show-installationrestartprompt issues


I have no clue as to where start looking as to what is causing PSADT to behave this way.

We have couple of win 10, 7 devices in our environement.
After the psadt has completed its tasks it is supposed to show-installationrestartprompt to user notifying them to restart their windows.

on some machines it works fine, while on others I see following in logs, not sure why it is behaving this way. Any help would be greatly appreciated.

What I want to understand is what is this [Asynchronous] calls and why this is going there, as in user forcefully has rebooted their windows then only it prompts user for reboot.