The black textures are actually non-square. Will try if changing that helps.
But, I am using the latest version and call setMipmap right after loading, so it's still a mystery anyway...
By the way, do you know of any way to detect if a device cannot display non-square, so I can add square ones as a fallback? I'd prefer not to make all textures square per default, e.g. with planet textures that would be very impractical.
And can the blackness also happen to textures that are only used for blitting?