Hi Boone, thanks for your answer.
The problem appeared right after upgrading WordPress 5.9.3 to 6.3. I have not updated any plugin.
I did the test you suggested and the following happens:
When I enter a group route like this: https://buddypress-example.com/groups/example-group/documents/
Only the user with administrator role can see the list of documents, other group members with lesser roles see the message “There are no docs for this view”.
Then I chose one of the documents from the list and went to its details: https://buddypress-example.com/documents/example-document
In this case, both administrators and other members of the group could see its content.
Then apparently it is something related to the “documents” view of the group that in its query decides not to show the list to certain roles. Even if individually they can be accessed.