New Forms: "Resolve Performance Issues"

I had this come up recently as well. I will see if I can find the form rule to remind me what it was.  I had the same thing though, it gives no feedback on what is wrong with the rule, all I can recall at the moment is  I ended up reworking how it evaluated the criteria.  It was something like instead of saying "when Field_A is unchecked" use "When Field_A is NOT Checked" and it accepted the rule.  So try re-phrasing your rule criteria a different way that filters the records faster than what you have.