Yep, it is a very strange bug. Since it blocks only some keyboard inputs, rather than all, I think the bug may be tied to outside programs not giving access to the keys for reasons related to how it is used in the programming. For example, the movement keys or the grapple input could use a different command/syntax than the jump input, and the bug could be specific to this command/syntax. I am not an experienced programmer so sorry if this doesn't make much sense.