UI Selection in GameObject dropdown out of place?

This issue is a little tricky to describe without detail, so I'm having trouble searching elsewhere. I'm trying to work with UI elements, but right clicking in the Hierarchy to create a game object won't present UI objects as an option. To add anything, I have to go up to the GameObject tab at the header bar and the UI dropdown selection is at the very bottom of that menu. This persists between instances of this project, but not other projects on the same machine. I assume it was a human error that caused this, but I don't know where to look for a solution, and this is seriously disrupting my workflow, so if anyone knows how to get the UI objects back into my right-click Hierarchy dropdown, I'd really appreciate it. Apologies in advance if this isn't quite clear enough.