We are experiencing some strange search results for our external users in our tenant. Internal users will for example see 9 documents in a search result, while external users for example only see 2 documents.
The external users can see and open/edit the documents in the document library, as expected. However, when searching either inside the document library (using the in-place search box), in the search box on the top of the page, or using for example the Highlighted Content WebPart, only 2 documents appear.
I could understand if the external users didn't see ANY documents in the search result. But when they actually see 2, where is the logic behind this? What triggers the hiding of the 9 remaining documents? And why?
Here is a list of the documents in the document library viewed by an internal user:
And here is the same list of the documents presented through the Highlighted Content WebPart (which is using Search).
So far, so good...
Here is the same list of the documents in the document library viewed by an external user. The external user has the same access level on the document library (and the whole site for that matter), and therefore sees the same number of documents:
But here is the result of the Highlighted Content WebPart for the external user. As you can see, only two documents appear.
I have found some related discussion on the topic, but none of them explaining this behavior: