Swapping a stack of items for an item already placed in a crockpot slot will result in all but one of the stack disappearing. (see steps to reproduce)
Might be related to the icebox swap bug from back in 2016, which I can confirm still exists in iOS Shipwrecked.
Steps to Reproduce
1. Place a cookable item in a crockpot slot. 2. Tap and hold on a stack of 2 or more cookable items different from the one placed in step 1. Slide the stack of items over the filled crockpot slot, release, and choose "swap". 3. The items swap: you now have the one item from step 1 in your inventory and there is 1 item of the stacked items from step 2 in the crockpot slot. The rest of the items that were in the stack are gone: not in inventory, not in the crockpot, and not dropped on the ground. (Expected behavior: 1 item from the stack is moved to the crockpot and the rest of the stack remains in inventory.)
This issue has not been confirmed by a developer yet.