Since we can't isolate components of compound path and shapes it is strange that Ai won't isolate a whole compound path/shape when you select only a part of it.
Try this:
1. Create compounds path/shape — like a torus
2. Use Direct/Group Selection tool to select only the inner circle if your torus
3. The 'Isolate Selected Object' button won't appear on the Control panel and the assigned hotkey won't do anything.

This should be fixed. Ai should allow to isolate a compound path/shape when you select a part of it.
Also, I think that Ai should be able to isolate these components in the first place: https://illustrator.uservoice.com/forums/333657-illustrator-feature-requests/suggestions/40684777-make-isolate-work-for-components-of-a-compound-pat