The Bug
Unlike pistons, doors, fence gates, the following blocks don't be activated even having redstone blocks adjancent them while placing.
Bell
Command Block
Dispenser
Dropper
Note Block
How to Reproduce
Place a Redstone Block
Place any block above adjancent it.
Linked issues
duplicates
Comments

Thank you for your report!
We're actually already tracking this issue in MC-51340, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote or any additional information to the main ticket it would be appreciated.
Please be sure to use the search feature before creating a ticket to see if the issue has already been reported.
Quick Links:
📓 Bug Tracker Guidelines – 🛠 Community Support – 📧 Mojang Support – ✍️ Feedback and Suggestions – 💬 Mojira Discord