Dimensions wont find main layer

[SHCanada2]

I moved this wall out on the floor plan SPV, the dimensions on the roof SPV moved accordingly, but if I move the dimension and then try and get back the dimension to the main layer, it will not snap to it.

 

Anyone seen something like this? 

 

If I delete it and then click on the auto exterior it then finds it correctly. But why doesnt it work when I manually try and snap to it?  

Edited 3 hours ago by SHCanada2