You nailed it - labor issues. This kind of stuff is as common as dirt with union goons. I used to work for a huge American company that shall remain unnamed, and I saw first hand what kind of damage union sabotage causes over the most trivial matters.
The term "sabotage" is French and originated with the French workers sticking their wooden shoes ("sabots") into the gearing in factories to stop work as a labor protest.
Yep. I worked in an auto parts plant for a while that spent a fortune air shipping parts to meet orders because whenever a small group of workers decided they wanted overtime pay, they'd start breaking things so they get their overtime.
It was only a few who appeared to be directly involved, the rest merely covered for them. Gave me a very low opinion of that union.