Hey everyone,
light probes always render themselves when moving them (since they have a new position and need to be updated for that). They also don't render when doing nothing. So using the render button, or moving them is effectively the only way to make them render.
But, once they have been rendered, they should keep that data. If you save it ofcourse

They should not turn black when restarting the editor. Do you have any error messages related to:
1. Failed light probe saving before closing the editor?
2. Unable to load certain light probe paths when opening the level?
Sincerely,
Kevin