My game used to automatically assign a truck to a new build etc (unless all of them were occupied)...

My game used to automatically assign a truck to a new build etc (unless all of them were occupied). Now whenever I start a new build, it asks me to assign a truck even though all of them are free.

Is this a minor bug? As it seems the game switches back & forth between both ways.

Just want to know if I can fix it as its relatively annoying....