After one of the recent patches, corpses were changed so that they are only highlighted if you have a corpse consumption ability slotted. Unfortunately, the Animate Blastbones ultimate appears to be missing this tag, which means you cannot see corpses with this ability slotted unless you also have another corpse consumption ability.
Please change Animate Blastbones so that if you have the ultimate slotted you can see corpses. Without this functionality, it is extremely difficult to effectively use an already gimmicky ultimate.