If you have something in your hands and you want to use other item in your inventory the action get stuck and u have to cancel the current action (the one you want to do in the first place) to do it again.
For example, with the mosin in my hands i found a kiwi in the floor and directly i used "eat", my character put the mosin in his back but nothing happened after that. I had to click again in the Kiwi, then "cancel current action" and then again "eat", after all that i was able to eat the kiwi and happens the same with a lot of items, if i want to craft a splint or use a bandage with something previously in my hands.