Error: Could not find Represents Company

Hi,

Since the recent update I get the message Could not find Represents Company when trying to save some of the previously created companies.
This message only appears with some companies, not with all of them.

What could cause this ?

My environment :

Ubuntu 18.04.5 LTS
Frappe 13.12.1
ErpNext 13.12.1

Thanks for the help.

Benjamien.