Please RDP to build worker and see what happens. I would recommend to add non-blocking RDP at init stage. Maybe you will see some interactive window pops up and waiting for input. If not you can re-run command which stuck in RDP session and see how it goes. Note however that custom environment variables are not available in RDP session so you might need to re-creates some of them.
You can de-activate the license in RDP too. However this might be not necessary. Build VM is transient and destroyed immediately after build. So not traces of your license stay anywhere.