DSP Readback/Real Time Display doesn't work for 1787 for MPx pins

I tried to check if MP1 and MP2 buttons work with DSP Readback and Real Time Display, but it doesn't read any value from the button when it is pressed or released. I tried various configurations for MP_CTRL and PIN_CTRL but it doesn't change anything. I also connected the virtual switch to readback, but even with zero comparator it was still displaying 0.