Arrows aren't shooting from a bow when using /execute /replaceitem

So I am running a clock that is running /execute to detect whether im on a lapis block and when I am is give me a bow using /replaceitem in my first hotbar slot. However when I try to shoot this bow it draws all the way and the arrow never shoots if im standing on the lapis block. Otherwise the arrow shoots fine. At first I thought that it was because /replaceitem is constantly replacing the bow when im on the lapis block, but if that was true I don't think the bow would draw.