The native ifc export does not yet meet the buildingSMART requirements for IFC.
If you generate an IFC export with the IFC Manager Extension, all data is properly exported to IFC.
However, the quality of the export depends on whether you have correctly classified the objects, added the correct information and uses the correct model structure.
In the situation that you describe. You import the generated IFC back into SketchUp.
When SketchUp imports an IFC model or object, the geometry is bundled in a unique component with the corresponding object information. During this process, the definition name gets a unique code. The object information will be imported and can be read via the Component Options.
Check the IFC export from SketchUp always in an IFC model viewer or checker. For example Trimble Connect.