KeyRelease won't happen until next KeyPress

Running Ubuntu desktop 18.04.4

When I reboot, everything is fine. But after some time (and maybe some combination of keys that I haven't figured out yet) my keyboard seems to get stuck in a state where my KeyRelease is stuck until another KeyPress happens. In other words, if I watch xevents with xev, then this will happen:

press key 'd'
   See KeyPress 'd'
..
press key 'a'
   See KeyRelease 'd'
   See KeyPress 'a'

I've tried resetting my keyboard setup a number of ways:

dpkg-reconfigure keyboard-configuration

And also:

setxkbmap -layout us
setxkbmap -option

This leaves me with:

% setxkbmap -query
rules:      evdev
model:      pc105
layout:     us,us
variant:    ,

And I've checked to make sure sticky keys are off:

% xkbset -sticky ; xkbset q | grep Sticky-Keys
Sticky-Keys = Off

But the problem persists. Disconnecting the keyboard and reboot do not help. It happens on multiple keyboards.