Addendum 2: A user in the Brightrock Games Discord server informed me that Shamblers and Restless Spirits aren't supposed to provide gold statues at all, in which case the bug goes from the opposite direction; The Aureate Monolith can turn both to statues if they die within range.

Small addendum: Tested Gild on Skargs, who also can't be targeted. Shamblers and Restless Spirits being unable to have Gild cast on them might not be a bug since they don't have wages or morale. Blood Money not working is still presumably a bug. Screenshot should still be an acceptable reference, mousing over with Blood Money displays the same lack of targeting outline but has the tooltip display.