What I expected to happen was....

Getting the advancement I made after I use shears on the pumpkin block

What actually happened was....

Getting no advancement, even if it does exist

Steps to reproduce:

1. Create an advancement that has the "item_used_on_block" trigger
2. Do /reload and wait
3. Check that the created advancement exists
4. Right click with shears in your hand on a pumpkin

Note: I changed the checked block ("minecraft:pumpkin") to "minecraft:chest" and it worked