It still does the same thing with your firmware with the reverse LPF delayed. I found that if I change H.backporch so the screen moves to the right and has a black bar to the left then it works fine. Its very strange because changing backporch does not affect R/G/B_act I think.
Your firmwares 0.80 reverse lpf delayed and 0.81 have glitches on screen on lineX5 mode. The previous firmware of 1 march works fine on lineX5. Is FMax on pclk_5x still around 160Mhz?
Everything else seems to work fine on 0.81