Quick answer: Unity Cinemachine cameras not blending because priority changes don't trigger transition? CM caches the active camera per-frame - set priority and call Notify to force re-evaluate.
Increased a camera's priority during a cutscene. CM keeps the previous camera live until the next scene-camera lookup.
Force notification
brain.ManualUpdate();Cinemachine Brain re-evaluates active camera. Trigger after priority changes that need to take effect this frame.
Use SetActive instead
For one-shot cuts, toggle camera enabled rather than priority. CM treats the disabled-to-enabled transition as immediate.
Avoid priority changes mid-tick
Schedule priority changes for the next frame. CM's per-frame caching favors stable priorities.
“Cinemachine optimizes for stable priority. Mutating it mid-frame fights the optimization.”
For cutscene cameras, use the Cinemachine Timeline track. The clip-driven approach has cleaner blend semantics than priority manipulation.