Hi, I have the same problem as OP but moving the password to a variable does not help.
The Desktop flow runs on a VM without any problems. The VM is always running and connected to the flow.
When I call the Desktop flow from a cloud flow with the password as input parameter, I get the error:
"Problem while executing action 'PopulateTextFieldUsePhysicalKeyboard'. Failed to write text in form field."
Curiously, when I start the Desktop flow from the Cloud flow, and then switch to the VM to see what happens, it does work. If I don't switch to the VM after the flow starts, the flow fails.
Anyone an idea? Something special I need to do to get this to work on a VM?