Contacts will not sync in iTunes - not using iCloud

Here's my specs: MacBook Air 13 inch Early 2015 running Mojave (10.14.3), iPhone SE running iOS 12 (12.1.4). I've been dealing with this for a while. I talked to a senior advisor back around October 2018, and he was supposed to contact me again, but never did. I began working on it on my own and have reinstalled my MacBook Air's OS a few times trying to fix it. I noticed pretty quickly that iTunes and Contacts were not communicating like they should, but never thought of it being a database that iTunes wasn't prepared to deal with. I just finished manually reinstalling Mojave and did not use any part of my Time Machine backups because I thought some corrupt file was making the problem. I now see that it is not the problem, because I keep having the issue. I uploaded my contacts to iCloud for the process to not have to use any 'corrupt' files, but to no avail. After reading this thread, I'm going to try going through all my contacts and taking out any "Son" or "Daughter" fields changing them to "child" and see if that changes anything. Thanks for the info.

So I went back through and changed all fields "Son" or "Daughter" to "child". I also took out my cousin's maiden name just to be safe and syncing through iTunes suddenly works! I wish I'd known this six months ago, but oh well, I'm happy I know it now. If anyone else has issues, I would recommend seeing if there are any new fields that were filled in in contacts.

Thank you. I have had this same problem for over a year on various iOS and OSX versions--I usually keep my Macbook, iPhone, and iPad up to date with the latest. I am currently using MacOS Catalina 10.15 and iOS 13.1.2. Local sync has always worked with Calendar, but has not worked with Contacts for a long time. Based on what Ganzhorn said, I went through every one of my contacts and deleted every field that had "son" or "spouse"--I did not have any other family-member fields in my contacts. I deleted them on my Macbook and my iPhone and then synced . . . it worked like a charm. I may run some tests to see if it is only certain family-member fields that cause this problem, but maybe not . . . I can always add family members to the notes. One other anomaly that I will share: when having this problem I could add a contact to my iPhone, local sync to my Macbook, and it would not show up, but then, if I local synced my iPad to my Macbook, the new contact would be on the iPad--the Macbook acted as a pass-through but would not show the contact itself. Thanks again to Ganzhorn . . .