Adding another power source to a line of powered rails does not update them.
What I expected to happen was for the extra power source to update the rails further down the track, making them powered.
What actually happened was that the powered rails further down the track did not update, and stayed unpowered despite the proximity of the power source
Steps to reproduce:
Make a long line of powered rails
Place a lever at one end and turn it on, ensuring that at least some of the other end of the track is unpowered
Place another lever halfway along and turn it on
The powered rails further along the track do not update
Related issues
Comments

Thank you for your report!
We're tracking this issue in MC-957, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki
Does MC-167257 describe your issue?