LTC6813 - RDSTATA & RDSTATB always returns 0xFF


I was trying to read the status register of LTC6813, where the status reg RDSTATA (0x0010) and REDSTATB (0x0012) always returns as 0xFF and the PEC also as 0xFF.

Apart from status register all other commands are working fine. I just wanted to read the die temperature, sum of cell measurement and other flags.

Is there any precondition to read the status registers?