Thanks for reaching out. This is unique & it might be a catalog-specific issue.
Where is the catalog stored? On an internal drive or an external drive? Has this started to happen since a recent upgrade of Lightroom?
Smart Filter works based on the instructions you have set. It could be loading results of all the images with Sport as a keyword. We can bring everything from an existing & probably damaged catalog to a new catalog.
Copy the primary catalog in question and place it on your computer's desktop.
- Press the OPT (macOS) when launching Lightroom Classic.
- Choose the option to create a new catalog and create a new one on the internal drive.
- In the new catalog, head to File > Import from Another Catalog, as shown below.
Proceed with merging the (potentially)corrupted catalog into the newly made, internal storage-based catalog.
For more help via video-based steps, check here. See Merging individual catalogs into a master catalog.
Let us know how it goes from here,