PostgreSQL version 12.0 has been available since October 2019. According to the compatibility matrix, version 12.3 is only compatible with PostgreSQL11.
When will Automic certify PostgreSQL 12?
Release : 12.3
Component : AUTOMATION ENGINE
PostgreSQL 12 Support is currently in backlog. The planned support/compatibility check is scheduled for after Automic v21 GA release which is planned towards the end of Q2.
The compatibility with specific AE version is yet to be determined (whether this will be v21 or the version thereafter).