The bug
Using a dispenser in combination with a sculk sensor doesn't trigger in some situations where a dispenser 'fails'.
These include:
Flint and steel when no fire is placed
Bonemeal when no plant is grown
Heads/carved pumpkin are failed to be placed/equiped
Shulker box failed to be placed
Shears fail to shear
Glowstone fails to charge a fully charged respawn anchor
Relates to:
MC-208331
MC-208333
MC-207300