One parent bp, two children, yet differences in world outliner

hi guys

this seems very odd behaviour, i have a parent bp just containing a few scene nodes to group static meshes and i have created two child instances of the parent and added some static meshes to each

so blueprint child one, in world outliner shows the full child node heirarchy under the bp instance and in content browser i can right click and create a thumbnail

however in blueprint child two, in world outliner shows no hierarchy under the instance and in content browser the thumbnail is showing already and the option to create a thumbnail is not on the asset actions menu

i cannot see any difference between the properties or content of these two children of the parent bp yet they are acting different

any ideas, this is irking me, would love to know why?