Oh that's odd, you should be able to grapple up and down as well. If not, that is definitely a bug.
Do you mean diagonal perhaps?
that is very very odd. just to be clear, you have to hold up/down and then press the grapple button to hook up/down.
if youre doing this and it still doesnt work, can you send me the following info:
thank you for your feedback! this will help me fix a potential bug!