Why isn't my guard minion training other guards?

Question

I've completed the guard hostage act of infamity, and now I have a guard in my base.

The problem is, he's one guard. I've asked for six to advance in the game, but he doesn't seem to be too interested in that. A few of my minions are also assigned to becoming a guard, but the training just isn't taking place.

I think the problem was my training room was ill fitted for this purpose, but I have at least one every item there.

Yet, nothing's happening. Why is this happening?

Answer 1

Had I hovered on the punching bag, I would have noticed the red outline - punching bags need room on both sides.

Items with red outlines are useless until moved, and without that punching bag I couldn't train more guards. Moving it solved the issue.