We are working on this chip and can happily use any decimation rates with sinc5 and sinc3 filters applied.
Only FIR doesnt work with 32 and 64 decimations , it starts working with 128 decimation resulting in a 64ksps rate.
FIR 128 OK !
FIR 64 not ok no answer , RDY not falling
FIR 32 no ok .. same thing no answer
Any hints why it doesnt answer ?? ...
Remark , we use the SPI reset with 1 high and 63 zeros at the beginning