So in testing I was using only a single spawn.
In the game I was using this for each trigger spawn point aka "splarge##":

marker_spawns = [splarge01,splarge02,splarge03,splarge04,splarge05,splarge06,splarge07,splarge08,splarge09,splarge10,splarge11,splarge12];

Apparently this is an issue, since it does not work the same  as:

marker_spawns = [splarge01];

Not sure why SQF doesn't like this? No errors in the game or logs.

next version: v2.6.5
  new PAR algo
 - find nearest medic
 - find nearest wounded
 - allow revive interruption
  add Dynamic sectors
 - Military sector can be used for FOB creation!
 
update sectors management (less network traffic)
update civilian management (better ai)
update side missions (veh perm)
update build menu
update squad panel

These are not linked to any waypoints.

Trigger is basic and is synced to a Warlords Sector. (I have also tried just having it as a stand alone trigger - not synced)
Any Player
Present
and null=execVM "SpawnEnemyUnitsLarge.sqf";

So the issue is:
The script runs.
No errors on screen or in the logs.
The units do not appears to be spawning properly in SP or server games now.
I only see the map markers where they should be spawning.

The units do not appear in the game in SP or server. Only on the map.
In a test VR room with a single player and the trigger point - script it works 100%. The units are spawned and are visible in the game and will begin shooting back.

Ask here about Reforger

https://forums.bohemia.net/forums/forum/401-arma-reforger/