Not certain if this is a Calamity mod issue, but when I googled it, someone else using calamity allegedly had a similar issue. When I enter a multiplayer world, grappling in any context causes me to be completely unable to use any items or exit the grapple state. If I try to enter a minecart, the fact that it uses a grapple to bring you to the track means that it freezes you in place. The only way I've been able to escape is to have my friend come to where I am and break the minecarts I'm stuck on.
#Grappling is bugged in multiplayer
green lodge
I have not tested whether this occurs when I actually have a grappling hook occurred, will try that out shortly.