I'm only asking for a solution... if you don't know that's cool. But I did see someone else have the issue, maybe there are more...
Not using a mouse. And it seems to happen at different random points.
ok - last try:
i can't help if i don't know
1.) your system and device? (windows/mac/android) (Tablet/PC/mobile)
2.) does the error appear always at the same point, or at different points? Also did you do some same action every time before the key function breaks? (like visiting some menu)?
3.) does middle mouse click work to hide, when H key does not? (if you don't use a mouse, can you use one for testing?)
Just to know "sometimes at some point something stops working" doesn't really help to figure out wheter something is broken or not.
I also could say "Well - it works here, so it's on your device" - would be the easiest way for me.
I also could say "Well - contact the support on the official site where you bought and downloaded the game" - would also be easy for me.
But i tried to help - still i am NOT an all knowing Jesus who can spot bugs just like that because "something broke at some point somewhere somehow sometimes"