What I did:
- Edited a View of Files
- Added File:usage:entity ID as a filter
- Exposed the filter
- Exposed the operator
- Selected an option and applied it.
I see these weird empty boxes appear below the Entity ID filter, but only in preview mode. When I save the view and use the filter on the actual view page, the boxes below the entity ID list don't appear.
Has anyone else seen this? What causes it?