Fresh install of 19.04 to see if it would fix the issue since I was also having it on 18.10.
If I let the system do a normal boot my keyboard stops responding (numlock key lit, pressing caps lock or similar doesn't toggle the lights) and I end up with an _ flashing in the top left corner.
Initially the system wouldn't even boot from recovery, so I installed the proprietary Nvidia driver (430) and now we're back to being able to boot from recovery.
System is running a GTX 1070 card with monitors connected via display port.
I'm really not sure of how I can debug this so any suggestions would be awesome!