The bug

Sneaking is supposed to prevent block interactions, so you can use the item in your hand even while looking at an interactive block. However, this does not work for many items, causing them to be unusable, even while sneaking.

How to reproduce

1. Get some food
2. Look at a crafting table
3. Start sneaking
4. Try to eat
→ You can't

Examples

The following items can be used properly while looking at an interactive block and sneaking:
Blocks
Boats
Buckets
Spawn Eggs
 Flint and steel
Fire charges
Firework rockets
Glass bottles
Armor stands

The following items cannot:
Tridents
Bows/crossbows
Food
Potions
 Armor (trying to equip it)
Snowballs
Ender pearls
Eyes of ender
Fishing rods
Eggs
Empty maps
Experience bottles
Book (& Quill)
Spyglass
Goat Horn

The following blocks are interactive, but properly allow you to use items while sneaking (possibly caused by MCPE-56968):
Dragon eggs
Bells not anymore due to the fix of MCPE-56968