Hi,
With EN bits set to 0010, the internal reference buffer is disabled, REF pins should be driven with a 4.096 V external reference and REFIN should be connected to 0 V in this mode. REFIN connection is through JP7, which is connected to 2.048V external reference on the board, thus the 2.048 you are measuring. Connect JP7 B to center to connect REFIN to GND, as needed. Also check the rest of the voltages as per Tables 1 and 3 before testing again.
Let me know what you find.
Regards,
Karen