LR Mobile doesn't correctly handle capture dates when the time zone of the phone changes. LR Mobile adjusts the displayed capture date to the new time zone rather than showing the original date/time as LR Desktop does and is specified by the MWG's Guidelines for Handling Image Metadata (2.0).
Here are the steps I followed on iPhone 6 / iOS 9.1 / LR Mobile 2.2.1 / LR CC 2015.5 / OS X 10.11.4:
1. Add a photo from the camera roll. LR Mobile correctly shows its capture date as 3/31/16 2:33 pm. The photo synced to LR Desktop shows the same date.
2. Terminate LR Mobile.
3. Change the time zone of the phone from Cupertino (UTC - 7) to Boston (UTC - 4) via Settings > General > Date & Time.
4. Start LR Mobile. The photo now shows an incorrect capture time of 3/31/2016 5:33 pm, adding the three-hour difference between the new and old time zone.
5. Make an adjustment to the photo and wait until it syncs to LR Desktop. The capture time in LR Desktop still (correctly) shows 3/31/16 2:33 pm.
6. In LR Mobile, save the photo to the camera roll and add that saved photo back to LR Mobile. Wait until it syncs.
7. LR Mobile and Desktop both show the capture date of the second photo incorrectly as 3/31/16 5:33 pm. The photo synced to Desktop has EXIF:DateTimeOriginal and EXIF:DateCreated as "2016:03:31 17:33:29", which is incorrect.