Invisible assembly

Hello
when I open a WWTP assembly, it doesn't display the 3D!
I can open the parts one by one in another window and there, they are visible BUT not the complete assembly!
Thank you for your help.

Hello;

Which version of Solidworks are you using?
Is the " 3D interconnect " step import option active?
Which version of the WWTP do you want to import?
With Edrawing, is the assembly visible?.
In the Solidworks options, what is the status of "Improved Graphics Performance" (system/performance option).

When you import the complete assembly: the parts are just " not visible ", implying: is the creation tree fed with the names of the parts?

I'm on Solidworks 2025.
I import in STEP (.stp) from CATIA 3DExperience.

No problems with some assemblies that I open in Solid (I leave everything as standard);
But for more substantial assemblies (automatic machine type) I have this problem.

The shaft is present with all the components.

The step opens well in Edrawing.

"Improved graphics performance" is checked.

Where can I find "The "3D interconnect" WWTP import option?