Been doing some digging into this and have discovered that the issue is that the dummy weapons I'm using are missing:
MuzzleChargeDelay = 0,
MuzzleSalvoDelay = 0,
MuzzleSalvoSize = 1,
Looks like the unitviewdetail.lua may not be seeing that this isn't a real weapon. Though I should be able to get the unit to work but the UI built menu will show all of the dummy weapons. See image below to confirm...
Unfortunately I can't use the weapon blueprint "DummyWeapon = true," as this would prevent the weapons from moving.