Tap Unlock. If Face ID fails, iOS lets you use your iPhone passcode instead.
Restore last backup first. Rackside keeps a copy of your data from before the last update.Start fresh (then import an export file). This clears Rackside; then import your latest export from Settings › Import from file….Restart Rackside. You can also add exercises yourself from the Exercises tab.
Check Settings › Permissions. If notifications are off, tap Open Settings and allow them. Reminders arrive 24 hours and 1 hour before each session.
Turn on Add to iPhone calendar when you create the session, and allow calendar access under Permissions. Events go to your default calendar.
Open the session on your iPhone and keep the phone nearby with Bluetooth on. See Apple Watch.
Your data can only be restored from an export file. See Backup and restore.
Contact Support.