When deleting the last searchlist replacement in the list of searchlist replacements it will delete all the searchlist replacements that have been set up.
We are currently evaluating this issue for a fix in a future service pack.
Steps to Duplicate
1. Click Administration tab 2. Click Search List Configuration 3. Click Manage Search List replacements 4. Click add. Add two Constituent based search list replacements. 5. Select the bottom search list and click Delete 6. Notice that all searchlists have been deleted.