Black Pattern in corners of HMD Pimax 8KX

I have parralel projection (Compatible with parallel projection) enabled. Still the effect is there. When I switch the FOV to “Normal” instead of “Large”, the effect is smaller for sure because the FOV is smaller.
The most remarkable thing is, it only affects the right and the bottom corner of the FOV. On the right 2cm and the bottom 1cm the instruments become hollow, knobs and switches disappear and at the Airbus the ocean disappears agains these black pattern… any idea?