Looks like it’s in a closed workset, hidden category, another phase, or otherwise just not visible in the view. Can you select the created element by it’s element ID in Revit and see if you can find it in a new 3D view with massing and all categories, worksets, and other info on? If not post an RVT with just that one family instance and I’ll have a look next week.
Thank you @jacob.small, for this interest in my case !
After deep review and tries, I found out the problem this mornig.
A famous “huge dwg-ish” geometry was the cause of this weird 3D reaction.
Interesting fact, no problems at all for the OOTB 3D data (in-situ, families), but this very way to create a family from dynamo does instantanly create a strange behave.