Bug

When prototyping a twisted vine farm, using a observer clock attached to a dispenser. I noticed that it just stopped working. When bonemealed it sometimes places a new twisted vine at the top with a separate age from the twisted vine below it.

Reproduce

Using a observer clock ( two observers facing each other) and its redstone output to a dispenser full of bone meal, facing a twisted vine. I had them inside a glass tube. I could reproduce fairly often.