Steps to Reproduce:
1. Craft a cake with open slots in the inventory
2. Repeat the crafting but with the inventory completely full (Even after items are added to the crafting grid){}

Expected Results:
Following java edition and the wiki, the now-empty buckets should stay in the crafting grid in BOTH situations.{}

Observed Results:
Milk buckets stack and stay in the crafting grid only when there is no room for them in the inventory. This is inconsistent behavior.

Additional Information:
This also affects addons. When a custom item is stacked to 1 (like milk buckets are only stackable to 1), the result moves to the inventory. But when a custom item is stacked to 2+, the result stays in the crafting grid as intended. See MCPE-57477 for more.