Steps to reproduce:
1. Plug in an iOS device
2. Click on either of the two cameras (see https://bugs.kde.org/show_bug.cgi?id=383255) that show up in the notification
3. Use dolphin to navigate to <camera>/store_*/DCIM/
4. Wait until the iOS device's screen locks
5. Wait another 5 minutes for good measure
6. Attempt to open one of the pictures visible in the Dolphin window


Expected results:
- The file is still available and the picture can still be opened


Actual results:
- A little bit after the screen locks, the directory structure becomes unavailable again, and trying to open anything in the Dolphin window gives you an error like "The file or folder /Apple%20iPhone%205%20(PTP%20mode)@usb:001,010/store_00010004/DCIM/100APPLE/IMG_0353.JPG does not exist." Files are only available while the device's screen is unlocked.


Reproducibility:
- The files do not become available again if you unlock the iOS device's screen and attempt to use the existing Dolphin window; you need to unlock the phone, close the Dolphin window and go through the steps to reproduce up to step 3 again. 

- 100% reproducible with all recent iOS versions (iOS 10.x+) and all iOS devices I had available (iPhone 5, iPad 2, iPad Air 2). Only able to test with Kubuntu 17.04.

- Not reproducible in macOS. The files remain available after the screen is locked.