It sounds like you didn't SAVE it. Let's try the same process again. Open the desired LEG to edit and then tap SAVE on the top right, close APDL, turn your phone off. Whether your phone is offline or not makes no difference, the sync system will detect that and not try to sync it. Now turn on the phone, open APDL and view the Leg. Are your changes persisted?
Please go to the Communication area of the app and submit a problem report if you require further assistance and we'll review your log files.
AutoFILL will only fill in empty fields so if you have data in there already it won't replace it. If it was empty my only guess is the data was not available from the cloud resources at the time you checked. I suggest giving the Flight Check area of APDL.net a try when something like this occurs and see if it matches, i.e. missing OOOI values.