Tangent relationship doesn't slide, 3 other identical (ish) subassemblies do

[areader0]

I've created what I think is a 4th collection of components and joints matching the previous three, but experiencing an odd behaviour that it won't slide on my rail like all other 3 subassemblies do. I built each subassembly up from scratch, but I believe I did them in the same way.

I don't have sufficient knowledge of Fusion 360 to troubleshoot where I've gone wrong. Can anyone see what the issue is with this file? In particular RightCarriageAssembly > RightOuterPanelAssembly

[areader0]

(FWIW I 'solved' this by deleting the subassembly and starting again - and the problem doesn't exist in the re-done work, so must've been an error I made somewhere, but I can't for the life of me see where)

[jhackney1972]

In my opinion, even when your Joints are all correct, you sometimes cannot drag all components in an assembly unless you define the motion.  As far as I can tell all your Tangent Relationships are fine and also your Joints.  All I did was to define the linear motion on that particular assembly using one Slider Joint.  Be careful is you upload my return model so you do not overwrite what you have.  Put it into another folder to be safe.