@ortles I have the same iPhone on the same firmware and no issues with my Vertical.
Make sure on the watch there is no SuuntoApp in BT connected devices. On the iPhone ensure that the watch is forgotten in the BT stack. Force quite the Suunto app Reboot (not restart) the iPhone by quick press Vol up, quick press Vol down then hold power button until Apple logo appears.Try to repair the watch, if necessary try restarting the watch and as last resort try a hardware reset.