All IDs that are associated with deleted saves on the simulation server load the 404 save. The reason it took a bit to update is probably just because deleted saves are removed from the FP in a step that takes place after you delete the save and there is a delay between the two.

@Beamngdriver (View Post)

 You don't need to delete saves if you don't want them on FP or don't want their votes to be counted in your average, unpublishing them is enough.

I think the 404 (a HTML status repsonse signifying that the page/object wasn't found on the server) is caused by caching. Caching is used to reduce the load on a primary server by storing frequently requested data (saves) on secondary servers and preferring to get data from the secondaries. The secondaries lag behind the primary server a bit so if something is deleted from the primary references to it will still be present on the secondary servers for a little while, causing intermittent errors like these.