It isn't me

I've paid attention, it isn't from choices I am making. I do things as they come up or when I can. So why is it when I am about to do something a person needs to stand right where I NEED to work after being in the store for twenty minutes. The entirety of the rest of the store is empty but I cannot work there I can only do what I need to do but someone needs to stand there suddenly when I am about to do something.