NO MORE THAN 4 MAX31856 amplifiers can one Arduino Mega 2560 read?

Hi all, I'd like to ask: can I connect no more than 4 MAX31856 thermocouple amplifiers to one Mega 2560 board?

I'm asking because when I tried to connect 5 or more MAX31856s to the Mega, I can only get readout from the first 4 of them. Is this a limitation of Mega board itself?

I'd appreciate it if anyone could help!

THANKS!

It's an SPI device isn't it?

Maybe it is a problem with the schematic you didn't post or the code you didn't post.