When you hold down q(or other drop item key bind)  the items stop dropping after you press an other button like W(walk forward key bind) but if you hold down W and then Q both work at the same time (you walk forward and drop items) which in my opinion is an inconsistency.
Edit:It is also the only action getting canceled(you can jump and throw items for example but only if you first hold down jump and then Q if you do that then it does both at the same time). And if you rebind the W key to Q it still works the same(it stops dropping) so the problem seems to be in the game (not hardware)