My conclusions so far after investigating this issue for half a year:
1. Many people still experience this issue after resetting location settings, so I discard this as the cause or fix.
2. This issue affects both Mac and Windows systems.
3. I solved the issue using a MFI cable and using the same iTunes, macOS and iOS version, so it may not be an iTunes bug or an iOS bug.
4. I hardly believe Apple brand sync cables CHIP may have a defect (hardware or software) that cause this malfunction.
5. Not all Apple brand sync cables seems to be affected.
6. I really encourage people to try MFI sync cables before considering any other option, or if all other solutions have failed, at least it was the only option that worked for me after a year of headaches!!!