How to Fix Fastboot OEM Unlock Waiting for any device

If it is a slotted device in Fastboot run the command: fastboot getvar current-slot and then set the active slot, fastboot --set-active=

Advanced features include Active When placed in an HDMI slot on a television set or computer monitor, the device turns that display into a personal computer

fastboot getvar currentslot try setting the slots again, without the space between -- It will return fastboot --set-active:a fastboot: unknown option – set-active:a

fastboot_ error_ failed to identify current slot stack trace: Error: failed to set active slot: Error: {error:{code:1,cmd:fastboot --set-active=b},stderr: waiting for any device >