Material Collection Parameter is blank

I found the solution and I’m posting here to save all of you the trouble. I hope you find this longer than it took me.

Open up whatever is blank, be it the MPC or a Landscape Grass type, whatever. When you open it, click on the window tab, and make sure that DETAILS in the top has a check next to it

Once you check that, everything should come back up and you should be able to use as normal.