Comparators not Updating Upon Cauldron Retraction

Upon unpowering the piston holding the cauldron, the comparator does not turn off until it receives a block update. It does not appear to be quasi-connectivity. The same occurs using a partially full composter.

What I expected to happen was...:
The comparator would become unpowered as it is no longer being powered

What actually happened was...:
The comparator remained powered, functionally and visually.

Steps to Reproduce:
1. Build up the configuration as shown. power the sticky piston
2. Remove the power from the sticky piston
3. Observe