User creation error again

[Rob K]

Running Ubuntu 19 I used the package repo to update with apt. 

chown: invalid user: ‘ossec:ossec’
dpkg: error processing package ossec-hids-server (--configure):
 installed ossec-hids-server package post-installation script subprocess returned error exit status 1

This happened on two of my VPSes and I've tried creating a user (there's already an ossec group) but to no avail. Have to hard remove everything and a fresh reinstall does not work either. Any ideas?