Maas-syslog breaks rsyslog (2.5.x)

We have a production maas 2.52 installation. The system is no longer logging normal syslog messages but the maas syslog entries are being properly logged,

We built a test Ubuntu 18.04.3 system and verified that rsyslog was working properly. We then installed mass version 2.4 and rsyslog still worked (this version has not implemented maas-syslog). We then upgraded to 2.6.0 and rsyslog stopped working - as with the production 2.5.2 install. If we stop and mask the maas-syslog service then rsyslog starts working again.

Any ideas would be greatly appreciated.