Solution
The cRIO expansion chassis are not compatible with NI-DAQmx like the cRIO 904x and cRIO 905x controller are. The cRIO expansion chassis only have the FPGA and Scan Interface modes.
However, you can use an Ethernet-enabled CompactDAQ Chassis with the CompactRIO system to expand the chassis and connect to the I/O using NI-DAQmx.