I saw that another user had this issue, and it was due to a coordinate addon conflict. I, however, don't use that addon, and I can't get the map button to show up no matter what I try. I'm not getting errors, so I don't even know what direction to head. I've tried disabling addons that might conflict with map functions, but no joy. Any ideas? I also can't get the square to go away when I choose a round map outline. That one doesn't bother me as much.

No idea unfortunately. The fact that your minimap stays square tells me you definitely have a conflict, possibly using some UI pack that tries to set a square minimap. Anyway, you need to disable all your addons other than SexyMap. Then enable 5, see if the button shows, enable another 5, etc, etc.

No response, closing.