Doesn't Pair with HR monitor – Zones - Cardio Interval Training Companion & Fitness Timer Review

I have a Bluetooth Polar HR strap (very common) and this app doesn't pair. It just sits there and then crashes. I have several other apps that do pair, so I know it's nothing wrong with my HR monitor.
Review by 5tick5tone on Zones - Cardio Interval Training Companion & Fitness Timer.