OK, thanks for this information.
Try force quitting iReal Pro from the multi-task dock, then launching it again and test.
If still faulty, turn off your device completely then restart, then check.
Other questions:
Is it the same bars each time or different ones?
Is it in different songs consistently or just certain songs?
Is it certain chord letters or any?
You could also run a backup (Settings>Backup), email to yourself, uninstall iReal Pro, then download it again from the App store. You can test on the exercise songs in there then restore your backup and test again.