Hello MJ,
The issue you're experiencing where selected locations keep disappearing from "Index these locations" and search results become inaccessible usually it is due to a corrupted database. Please try the next:
a. Open "Indexing Options" from the Control Panel.
b. Click on the "Advanced" button.
c. In the "Advanced Options" window, click the "Rebuild" button under the Troubleshooting section.
This will initiate the rebuilding process, which might take some time
If you suspect that some location may be giving some trouble, such as external drives,folders with thousands of files or long directory path, you can try excluding that path from Indexing:
a. In "Indexing Options," click on the "Modify" button.
b. Deselect the problematic location from the list of indexed locations.
c. Click "OK" to save the changes.
Other than that, you can attempt a verification of system health and restore though the steps in the next link:
- Perform a DISM health check and repair: https://learn.microsoft.com/en-us/windows-hardware/manufacture/desktop/repair-a-windows-image?view=windows-11
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