According to MC-61 it is or rather was intended that the coat of a sheep is visible for an invisible sheep. However in the last versions this is not the case anymore:
Example command
/summon Sheep ~ ~ ~ {NoAI:1,Health:0.1,ActiveEffects:[{Id:14,Amplifier:1,Duration:2000}]}
Related issues
is duplicated by
Comments


Probably because fixing it back then would have been harder than it was whenever it was changed.
I thought it was intended that it is not invisible?