Wont boot if USB keyboard attached. Will boot fine if no USB devices present

AML-S905X-CC boots fine and is a fun device. However, if I leave the Kybd/mouse in while booting, the startup process waits/hangs at “starting USB… … USB XHCI … no EFI System partition… Welcome to GRUB!”. At this point I need to unplug the kybd, reboot, and all is good. If it matters, I’m using an 2010 vintage Dell USB kybd.

Update: Seems like if I let it linger at the “Welcome to Grub!” state for 5+ minutes, the display timesout/blanks - a keyboard press seems to get it moving forward, and the device seems to boot. Dont want to wait 5mins for a usb timeout.

Is there a grub-config option I’m missing?

Which image are you using?