@Gargron Sometimes a clean install is the best bet. There are sometimes changes made that don't jive well if old packages and configurations are there. It could also just be a driver issue; back in Debian 9 my Corsair keyboard and mouse wouldn't work unless I pulled in the backports kernel, and even in Debian 10 my Lenovo touchpad doesn't work in the installer, but is fine after the system is up and I've installed the non free firmware packages.