I tried for an hour trying to figure out those two mining zones. They bug out very badly. For one, the zones are horribly inconsistent, showing me "out of range" when standing right under a mining laser.
At some point I just gave up on them. In fact I am amazed you could even deplete the southern one. I can get it to fair or good but then the buggy interaction with the other zone screws me over.
Most of the mining zones bug out on me in some way. I have often gotten depleted blue zones turn white unless I reload an older save. This is probably low on their priority list but I hope they could fix it. Maybe move one of the zones further away from the other.
As a fix, have you tried flying off planet and then landing again? That seems to reload everything and may fix any weirdness.
