Hi Wick,
After seeing the model it was very clear where the errors were being generated.
The issue you’re seeing with your model is that it’s got a lot of Ngons (any polygon with more than 4 sides). This can definitely cause the types of issues you’re seeing.
You would really need to grab the edges of the circles and cut the edges in to get a better result.
This is a simple mesh with a hole in the floor with the edges cut to meet at the corners.
Here is a link to the file I created if you need/want to take a look.
If you have any other questions feel free to ask!