Is there a max number of Contacts cards?

[iMore Question]

I have a LOT of Contacts cards 1000+ in about 15 groups. When I type or copy/paste information in the "notes" area and hit edit/done the information disappears. I have to retype the information again. This 'bug' started before Mojave upgrade and has gotten worse since upgrade.
Contacts Version 12.0 (1882)
macOS Mojave version 10.14
iMac (21.5-inch, Late 2015)
Processor 1.6 GHz Intel Core i5
Memory 8 GB 1967 MHz DDR3