auto change spotter?

[Wdll]

I noticed somethign happening for the first time and I wonder what is the cause. Rule or whatever.

While in the rest of the battle I had no problem, this turn I noticed my forward observers (first discovered it with my favourite G0, couldn't call a strike. I click on it, hit B and the strike screen had the main HQ as the spotter.
I clicked on the order strike button, the same result. I tried with a different forward observer, same thing.

I have never seen it before so, what gives?

This in an ongoing PBEM campaign.