John, I agree with you. I am on a Windows machine. Same problems tho.
Simplify went wrong after Version 3 to me and has just exacerbated in faults. It seems to me that Topaz cares more about moving ahead of their competition these days, than fixing existing problems. Simplify problems should be on their important list, seeing it is a part of Studio.
Part of the problem - as I see it - is that Topaz seems to have tried to solve the 'spider' appearance, but in doing that, has reduced the quality of the photo into a blurriness that cannot be fixed by adjusting the opacity. Certainly the 'spider' appearance can be a problem, but is easily fixed. I remember seeing a Topaz webinar years ago to fix this. I have managed to fix it myself with masking, but still retaining the Simplify effect.