When blazes are spawned they refuse to pathfind, instead they stay in place jumping up and down until they are aggravated. I have tested with virtually every other mob in the game (save endermen and guardians), and they will all pathfind to a solid block.
Thank you for your report!
We're actually already tracking this issue under MCPE-45469 so I've requested this report be 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:
📓 Issue Guidelines – 💬 Community Support – 📧 Customer Support – 📖 Game Wiki