I had build multiple Enlistment Centres and selecting a rally point for troopers after reaching drop pod upgrade and suddenly all of my Laborers turned into Troopers with out pressing call to arms. My economy got busted complelty becouse I did not notice this at first. I was forced to calldown a Supplybunker to get Laborers.
I cannot replicate this, seems you maybe pressed a hotkey by accident? I have never had this happen past or present.