I've included some pictures and the project file to illustrate the issue I'm having. This seems to be happening with any STL file that I open on Cura. I can't select this circular shape that generates on the corners when opening the STL file, so I have no way to get rid of it. For this example with the golf tee, it doesn't take up much space, but with bigger pieces I want to print, the extra circular piece I want to get rid of gets bigger and takes up much needed space. The STL files were made using Fusion 360 and I ensured that the only body that existed was the Golf tee as shown. Any help in dealing with this would be greatly appreciated.
Golf Tee Test File.3mf
