This ticket is basically identical to MCPE-11583, but for mooshrooms, mushroom stew and bowls instead of cows, milk and buckets.

To reproduce

1. Ensure your hunger bar is not full
2. Place a single bowl in your hotbar and select it
3. Click "Milk Stew" button when next to a mooshroom
   Observe your player immediately consume the mushroom stew"

I expected the mushroom stew to replace the empty bowl in your hotbar and the player not to immediately consume the stew.

If you try again with a stack of bowls, the player does not immediately consume the stew, likely because the selected item does not change from an empty bowl to a bowl of mushroom stew. I have no clue why there's a difference when using a single bowl with touch or mouse input.

Tested in single player survival on Samsung Galaxy S6 (SM-G920W8), Android 5.1.1 and Asus B121 Tablet Win10 Pro x64 10.0.10586 build 10586 (using touch input, I cannot reproducing using mouse input)