Well, I removed the RED units I purchased and saved the game. I then reloaded it, added RED units and deployed them, with a facing towards the BLUE forces.
But still when I load the game to play, I play as blue. As soon as my unit spots a red unit, I click the red unit and TAB, so I am seeing the red unit from it's facing, and they are definitely facing away from the blue force...which is why they're not firing (although one would think they may turn and fire back, regardless of where the enemy are coming from!)
Also, when I select all my blue forces and march them forwards, once the pass the red forces, all hell breaks loose. So the fact that the blue forces are being ignored up until they are in LOS (even though they have been firing at red!!). So it's clear that the units are facing the wrong way.
I've tried the "Red Friendly Area" of the map on several different settings, but to no avail.
I've spent a day on creating this scenario and, tbh, it's not worth carrying on.