I can't change the appearance of the stroke on this polygon to anything under 4pt stroke, and I can't change the corners from anything but round joint. Turning off the stroke does nothing, and only change the stroke size above 4pt changes the appearance. Even then I can only change the stroke weight, nothing else.
When I create a new polygon, it's fine, until I save the file and load it up again.
File was created on a 2018 version of AI on a MAC. File has been edited on 2018 and 2019 versions of AI on a PC as well.
I am a student, so switching between versions and PC/MAC is mandatory because I have to work in class and at home.