Vanilla/ modded items wont work

[MasonsAlive]

Been playing with my friend the past week and everything has been fine and working normally, until today. My backpack wont open (the only modded item so far ive found), along with my anvil , loom, and basic furnace all wont open at all. tried resetting my key binds but nothing has helped. like i said, just about everything else opens. need help figuring out what the issue may be so this server will work again. (Note: i also have the essential mod, project e, and ultimine mod installed into the pack, at the same version everything else is)