Pumpkin / Melon stems aren't detected by observers.

The observer will detect melon/pumpkin stems in their growth stages. However, when the stem has fully grown and is able to produce melons/pumpkins, the observer no longer updates when the stem creates either fruit.

 

On Java edition, this issue doesn't seem to be present. Observers will detect all the growth stages of melon/pumpkin stems, including when the stem grows an actual melon/pumpkin.

 

This makes automatic farms much more difficult to build on Bedrock.