[PatG]

Ok I got it - Both the artillery units you selected (OOB 034 units 335 and 333) are class 16. According to the guide, class 16 is:

UnitClass 16=Infantry Support Gun

Now for direct fire type Infantry Gun only - use UnitClass 154 Infantry Howitzer for indirect IG firers.

So the formations you chose were both direct fire only and you won't see them on the arty menu. Try selecting different gun formations including off board to ensure there is no other problem.