Official comment

This came up recently here:
Update your battery firmware and you may also need to open the DJI app to reauthorize the flight zone between flights if the battery firmware doesn't do it.
For future reference, you can always start up where you left off by tapping any corner waypoint while the blue verification line is showing.
https://support.dronesmadeeasy.com/hc/en-us/articles/115005940746-Manual-Restarting-Point
We have attempted to fix this issue in 5.9.0 that was released yesterday.