Basically, when I try to launch an emulator (old one or created from scratch doesn't change anything) I can see the phone's frame but Android doesn't boot.
Sometimes on the EventLog window I can see this error
Emulator: Critical: UpdateLayeredWindowIndirect failed
I tried many combinations of OS and phone but so far no sign of life, so I guess it's not related to any new update.
I'm currently using AndroidStudio 3.4 (but I had the same problem with the 3.3 version) on Windows 10.
Update: the error reported above appears only if I move the emulator to the second monitor, so maybe it's not related to the main problem.