When I tried heater 3 the first time I was still using I1 instead of I0, so I tested this again and I was able to get it working with heater 3 and PWM1
I tried heater 7 and PWM5 again, that still isn't working. I may test some of the other configurations just to see if this is isolated to that connector, but I don't have any plans to use heater 3, so I might just call it good as long as everything is working.
Thanks!