This problem seems to only happen sometimes.
Normally, when I hit the key combo WIN + right arrow, it sends the current window to the right half of the screen. WIN + left arrow sends it to the left half of the screen.
But sometimes (after I've had the screen locked) instead of sending the window to the right, WIN + right arrow sends me to TTY3. Typing WIN + left arrow takes me back to the graphical desktop, and then the window snaps to the right.
Similarly, when this problem occurs, WIN + left arrow takes me to the login screen, and when I'm there, WIN + right arrow takes me back to where I was, and then snaps the window left.
ALT + F4 also sends me to TTY4 (and similar numbered TTY for other numbered function keys).
My system is "typical" (Dell optiplex + Ubuntu 18.04, no dual boot, no weird partitions) except for the keyboard, which is a Kinesis Freestyle 2.
The normal keyboard shortcuts for these various screens still work, i.e. CTRL + ALT + F1 takes me to the login screen, CTRL + ALT + F2 takes me to the GUI, CTRL + ALT + F3 goes to TTY3 and so on.
I really like the WIN + arrow shortcuts, so this unexpected context switch is driving me crazy. Any suggestions?