Coupling problem: bug maybe?

I discovered that the couples of my tram went missing (well, technically I found out this a few weeks ago, but forgot it).

If I add the models of the coupling to the animation of the coupling (coupling type animation), they just simply doesn't appear in LOTUS. If I don't select them to the animation, they don't disappear, though they don't move then.

I don't have any visiblity variables on them, only the coupling animation (which is parented to the coupling settings in General options).

I have absolutely no idea what can possible cause this. If I couple this tram with the GTN (I know it's not really realistic ) I get another interesting issue:

(I don't know if this is a bug maybe, or I made up something, that's why I opened this thread here)

My only problem is that this setup worked until a few weeks ago. Then, maybe after a path (I don't remember unfortunately), it went like this.

I checked the scripts and the settings (animations, general settings), but I didn't find anything:

(E stands for front, H stands for back, so csatlas_E refers to the front coupling, and csatlas_H refers to the coupling at the back.)

Oh crap...

I thought it was a setting to parent the animation of the setting to the coupling itself. Of course now works great.