Tri-level Autoracks, coupler issues? (newbie mistake)

Hi Rob, it was on a 195mm curve so It might just be too tight then. Will see what I can do about the couplers but might have to go for shorter sets of cars or mix them up in another way.

Thanks for answering.

Blimb was supposed to have been "climb" but yes, that's probably the issue. It looks like I do have space enough to change the 195mm to 220mm so I'll start by giving that a go.

Check and Re check your track work. More often than not improper track work is the problem. If you have a incline make sure the transition from flat to inclined track is gradual. A sudden transition from flat to inclined track especially on a curve can cause the problem you described.

Example; take 2 pencils and lay one flat on your desk now lay one end of the other on top of the first one. Creating a "T"
Notice how high the end of the one on top is off surface.
Now holding one end of the pencil on top to the desk and slide it forward over the other one creating a "X"
Notice how much higher the other end is now.

This is exactly what is happening to your couplers as one car enters or leaves a incline or decline and the next one is still on the flat area. One coupler is simply lifting up higher than the other causing them to uncouple.
Being on a curve only makes things worse as it creates additional resistance (drag) and can increase the miss alignment angle.
The fix is to have longer gradual transition to the incline. This will help keep the couplers closer to the same elevation instead of one low like the "T" and the next much higher like the "X"