As of 2020 help indicated this was not possible. When I tried it today with a guest account that had editor permission I was unable to modify the filters in the report.
Is there a way for a guest user to filter a report, even if only modifying an already applied filter.
To make this more explicit I have a report with a text field. I want guests with at least editor privileges to be able to search for a given word or phrase in that field. As the licensed user I created a "contains" filter on the field that works well. I want the guest to be able to modify what that filter searches for.
