Confirming a name suggested by face recognition breaks the current Keyword column in the Metadata browser, such that the column won't display the photo with the confirmed name. To reproduce:
1. Create a new catalog, enabling face recognition.
2. Import two copies of the same photo containing a clearly recognizable face.
3. Assign both photos the keyword "John".
4. In the Keyword List panel, click the arrow to the right of "John", which opens a Keyword column in the Metadata browser with "John" selected.
5. Select the first photo, go to Library Loupe view, and enable the viewing of faces by clicking the Draw Face Region in the toolbar.
6. Label the face with "John".
7. Move to the next photo, which should show "John?" above the face rectangle. Confirm that name by clicking the check mark.
8. The current photo disappears from grid view, even though the Keyword column shows two photos assigned to John:
9. Disabling filters and re-enabling them or re-clicking on the arrow to the right of "John" in the Keyword List doesn't bring back the second photo -- it still looks like the screenshot.
The Keyword column is now permanently broken. There are two workarounds -- 1) restart LR, or 2) add a second Keyword column and delete the first one.
Tested on LR 9.2 / Mac 10.14.6.