Z87 Extreme6 no longer boots from usb mouse

[philo]

Although I changed nothing in the bios, suddenly the same keyboard and mouse that used to turn on the pc when enabled in legacy bios do not work. The pc does not respond to the space bar key or mouse clicks at all. I reset the MB to default settings except for allow start by usb devices.

I did have occasion to reset Windows 10 recently but I don't think that's relevant, is it?

Thanks.?