Contacts on my iMac disappeared == so now they are also gone from my phone
I have an iMac [Mojave] and iPhone [12ProMax] - I was working on my iMac and did a backup of Contacts to ABBU file [fortunately] then cleared it out and did some other work and then reimported the ABBU file == it stayed there but then I noticed Contacts were totally missing from my iPhone [the app was there but all 400+ contacts were gone other than about 5-6 recent ones] and then I looked into All Contacts on my iMac and it is totally blank, other than 2 I recently used.
So I restarted and then imported the ABBU file again == did some work and then poof! contacts disappeared entirely other than those 2 recently used.
iMac 27″ 5K, macOS 10.14