I have heard from several users who are experiencing problems using the app after upgrading to iOS 12 and Watch OS 5. Please bear with me as I update the iPhone and Watch apps to work with the latest software updates. It will be done ASAP! In the meantime, please sync your treadmill run data the old, boring way (i.e. manually 😜)
Treadmiler requires an iPhone, Apple Watch and an account with MapMyRun (if you want to sync with a 3rd party service). Future app updates will include support for Strava and RunKeeper, so check back soon if this you use one of these services!