NX Geometry created at assembly level is automatically placed in the component.

In NX1884, creating geometry at the assembly level with selection filter either set to "Entire Assembly" or "Within Work Part and Components", NX would automatically make the component the work part and geometry are created, not at the assembly level. 

Solution

This behavior was introduced starting in NX1847 because of the new "Allow Automatic Work part change" project. By default, this option is On. When this option is On, the first selection in the dialog will change the work part automatically to the part of the object selected. 

 For a quick change of this behavior in the existing NX session, you can use "Allow Automatic Work Part Change" button in the selection tool bar next to the Selection scope (in NX1872) as below:

And in selection menu bar from NX1899 onward:

Either you can change the Customer Default from: File --> Utilities --> Modeling --> General --> General --> Allow Automatic Work Part Change if you don't want the service permanently or you can switch off the toggle button if you want to go back to old behavior quickly. 

Notes and References

Hardware/Software Configuration

Platform: INTL64
OS: windows
OS Version: 1064
Product: NX
Application: ASSEMBLIES
Version: V1884
Function: ASSEMBLY_MODEL

Ref: 001-9598358