I am getting the same error in Enterprise 10.8.1. I am able to restore a full backup, but then when I try to restore the incremental backup, I get the same error that the OP gets. It references the data store, but PITR is enabled on the source and destination data stores.
YES! We are having the SAME issue on 10.8.1 and working with support, to no luck yet. Anyone have any case numbers to share so our analysts can get together on this one? Our case # is 02798351
The bug is specific to having the tile cache data store registered, but not included in backups. If you don't publish scene services, including the tile cache data store in the WebGIS DR backup shouldn't increase backups times, (and work around the bug).