Can't Milk cow or suspicious stew a mooshroom!

I can't milk my brown mooshroom with my bowl even though I fed him a dandelion, so I tried milking a cow to see if that would work but it did not and so I am reporting this glitch. Only occurs in creative mode.  I tried multiple spawned (using eggs and /summon) mooshrooms/cows with the same result. Tried with a fresh save and was able to recreate glitch.