Great feedback! Thanks! I'll check out why the grab doesn't work. An initial thought that comes up is that the grab triggers twice in quick succession, thus grabbing and releasing instantly.
Yeah, the box physics is wonky at the moment haha. It is one of the next todos. I know what the issue is. Long story short, grabbing an object which sits below another gives a quick impulse force onto the one on top. Also, grabbing an object "overrides" the forces and blocks, meaning the block can be pressed through another one. In other words, it is an issue with high prio.
Thanks for all the valuable feedback!