Recently, entity IDs were changed to make them consistent with block and item IDs. Then the /locate
command was added and it has the same ID format as the entity IDs did before they were changed to make them consistent.
For example:
/locate Village
Compare with
/give @p minecraft:wooden_door
/summon minecraft:villager
IMAGES:
/locate vs /summon and /give
They are also case sensitive.
Not a bug.