If your drone has an anti-collision system it could be cheated by the sun.
If it’s active and even if there aren’t any physical objects in front of it, the drone could be stopped in air (of course it will still fly!)
It happened to me several times that the sunlight of the first or last hours of the day was mistaken for an obstacle.
That’s because in this situation light has a low impact angle that hits the Obstacle Avoidance System straight from its front.
And the drone preserves itself stopping.
At sunrise and sunset the sun is “low“.
To keep on flying you can rotate the drone a little bit on its axis (yaw) so that the sensors are no longer hit almost orthogonally.
You can move forward with a lateral translation component.
It should take so little.
However, you will not have to wait long before the sun rises and problems will disappear.