I've had this problem, usually let it sit for 3-4 minutes and if nothing happens I just hit the 's' key. All GPU's then pop up, don't know if it'll work but might help.
I would do this, but the command executes and then the program exits. If you take a look at the pic
https://imgur.com/a/3ai7Xir you will see that the command prompt is ready for a new command. If I hit the s key, it will just be a string on a command line with no executable.