itch.io

I think some on keyboards, if you hold down two keys at once, it won't let you press certain other keys. Which keys exactly are blocked by other keys depends on the keyboard. 

Try using a different key for Grab. There are four default ones (X/V/J/L) and it can be changed in Key Config if none of those work.

You can use this site to test which keyboard keys you can press at the same time: https://www.mechanical-keyboard.org/key-rollover-test/