What does a box in a triangle mean?

[Fredashay]

I have an industry that's not producing anything. It has a cardboard box inside a triangle icon over it. What does that mean?

[JennyTheGhoul]

Without actually seeing it, I do believe that means it doesn't have any materials with which to produce inside the building.

[Kunovega]

storage problem, depending on which icon you mean it's either empty (not having input brought to it) or full (not having product taken to the docks or another industry building)