Sorry about the late reply, please try :
1. Virtual keyboard : while in-game (playing free mode) > Tap Windows key then type keyboard, you should see the "On-Screen Keyboard" option, click on it > while the popup keyboard is active, return to the game (the popup will overlay the game) > now holding Alt (to move cursor), tap on the popup keyboard's CapsLock button (button on left side). Note: you can minimize this keyboard, and bring it back up with Alt[hold]+Tab[tap several times until it is highlighted].
2. Send me a bug report (check in the game description at the end on how to do this, it's just a few clicks ;) )
SideNote: if 1. Virtual Keyboard solved the issue then there's a high chance that the issue is from the physical keyboard, if not then it's either keyboard setup (which you confirmed to be USA, so should be ok) or a game glitch.
Cheers,
~NK