Jimbo, have you tried removing all keymaps (aka input sources) and re-adding them? I heard this helped occasionally, at least before Trusty. In Trusty the settings panel can be reached with
unity-control-center region
The workaround back then was to run (for French keys)
setxkbmap fr
This would pin the keymap down for the current session at least. Does that still help?
Jimbo, have you tried removing all keymaps (aka input sources) and re-adding them? I heard this helped occasionally, at least before Trusty. In Trusty the settings panel can be reached with center region
unity-control-
I'm not sure about the later comments, but your initial description sounds like old bug /bugs.launchpad .net/ubuntu/ +source/ xorg-server/ +bug/837456
https:/
The workaround back then was to run (for French keys)
setxkbmap fr
This would pin the keymap down for the current session at least. Does that still help?