ill check it out
Mao marker is in the comm and is linked to center ref and everything works fine with vanill supply lines ,had a quick look but i cudnt see "myMapMarker" should that be in teh scripts of the workbench?
"myMapMarker" is a hidden property of WorkshopScript. Usually, the workshop initialization quest would fill it. It doesn't work, if the cell where the marker is placed does not have your settlement's Location. Which, I suspect, is happening here. This is an interior settlement, right?
IMO you have to add a new quest with StartGameEnabled, which puts that specific MapMarker reference into that particular propery.
More details:
For interior settlement, you usually have to take at least the one exterior cell at the entrance, and flag it with your Location. That's what I did for Lechmere Subway Station, for example. (The Mechanist's Lair is also set up like that, but Vault 88 is not. These is some custom stuff going on there, which I don't fully understand...)
This would fix it for new players, but it doesn't work retroactively. If someone has your settlement in their save, then the init quest happened already, and it's too late.
Mh, is nice from you to link the MapMarker to the CenterMarker, but this is not standard setup. Bethesda settlements aren't doing that. So adding code which follows links like that to find a MapMarker would probably only fix your settlement...