Advanced Search on Event Type OR Address returns only Event results

Searched for issue, could not find a duplicate. Reproduced on 'master' site.

How to reproduce:

1. Choose or create 2 contacts who have the same city

2. Register 1 of those 2 contacts to an event

3. Register 3rd contact who has a different city to the same event

Test
4. Advanced search using "OR" operator for: city or participant at this event type. Should return all 3 contacts should it not?

5. Instead it returns only contacts #2 and #3