I've got my laptop installed with Windows 10 and Elementary OS. First I installed Windows and second Elementary OS so I get a boot menu from Elementary OS. I have got an external mouse connected on a USB drive and when I start the laptop with the mouse connected, the bootmenu does not respond to keyboard input. When I disconnect the mouse and restart the laptop, the problem is solved.
It is not only the mouse, it is with every external USB device.
The laptop is a 2019 HP Spectre X360.
I hope somebody can help me solve this problem.