Originally Posted by
Dargaron
The problem can't be with the Port Garrison, since Revan the Great said he got the event notification for finishing the Kingship Reform, and that requires a Port Garrison building.
Have you built the first level of Hellenistic Military Colony? In my semi-recent Macedon playthrough, I had to build a lower level of government (after completing the Kingship Reform), construct colony level 1 (which is kind of odd: why am I colonizing Macedon with Macedonians?), and after that, I was able to build the Basilike Patris.