Simple SharePoint search <MANAGER_PROPERTY>:<VALUE> returns only subset of items.
E.g., you have 100 unique customers on a list with same managed term defined in a field, and you try to return all active customers with query “Status:active”, but you only get few hits from search.
I’m using on-prem SharePoint 2013.
Disable TrimDuplicates in your Search Results Web Part settings or in your Query XML by setting <TrimDuplicates>false</TrimDuplicates> ALTHOUGH the items are not duplicate and only thing in common is this one individual value.
Works? Yes. Makes sense? No, this is SharePoint.