I haven't found a solar cover for the Oasis for sale.
So as far as I can tell it's just a rumor/discussion and not an actual product.
As for charging errors, I get those with the walnut cover from time to time. When they happen I just remove the cover and reattach. I think it's probably just the contacts slipping out of alignment.
I will also report condition and charging once the new cover arrives (tomorrow).