Here is what I get when I slice your model.
I have put a brim around the outside ONLY. I have an item I print that is very similar in size and shape, smaller though. My brim thought process being that the circular portion has very little contact with the build plate.
Of note with the supports is you have a threshold of 15 set which I ran with. Recently the default has been 30. I believe in the past it was some other value. Is your firmware current? I know some folks have had issues with firmware and so have rolled back to older versions.
Printer 01.05.02.00
AMS 00.01.06.62
AMS 2 Pro 02.00.19.68
Brim setting
Supports
Speed
