I’ve had similar problems on Windows 10.
Turned out the QMK Driver Installer installs drivers for every possible bootloader / controller by default, this confuses Windows and it doesn’t properly detect the keyboard when in bootloader mode.
Solution which worked for me was:
1.) put keyboard in bootloader mode
2.) find it in the Windows Device Manager (was under “Other” for me)
3.) Uninstall the device
4.) Download the .zip version of the QMK Driver Installer from here: Releases · qmk/qmk_driver_installer · GitHub
5.) Unzip to some temp folder
6.) Put your keyboard in bootloader mode (if it isn’t already)
7.) Run “install_connected_drivers.bat” from the folder where you unzipped the installer. This should detect your keyboard and install only the necessary driver