Powercfg /requestsoverride doesn't work

I added a problematic device with the powercfg /requestsoverride driver devicename system command.
And I can see it listed when typing just powercfg /requestsoverride.
However, when I type powercfg /requests, it's still there and it's preventing the PC from going to sleep automatically.

I've done this in the past with the same device on Windows 7 and it worked as expected, but it doesn't now on Windows 10.
I did enter the name properly (even tried various combinations later) and I did restart, several times.

Searching a bit, I see that others have the same problem, but I'm hoping someone here can come up with a solution.

Windows 10 64bit 20H2.

The motherboard is a P55 Gigabyte and the device in question is an old PCI SB Live! with KX drivers. Everything works fine, except that it keeps the PC awake. (It's the same in W7, except there the /requestsoverride command works as it should.)

Make sure driver/device is not in use terminate process using the driver/device and execute the command.

Update: automatic sleep works now, for some reason. The driver is still listed if I type powercfg /requests, but apparently it doesn't stop automatic sleep anymore. (It did do that before, I confirmed it by disabling it and enabling it and comparing the results.)

IDK what may have caused it. The only changes I've made is that I added various combinations of the full driver name to the /requestsoverride command, that is: not pasting the entire line as outputted by /requests, but just parts of it. Maybe that helped for some reason, or maybe the additional reboots helped... who knows.