The I2C SDA and SCL signal voltage at the expansion [socket] card of the kit is 3.3V and was expecting 1.8V. Is there DIP switch setting or other component changes on the USB motherboard that allows the I2C pullup voltage to be set to 1.8V? The Timing Commander [V1.17] software shows a warning message about not finding the 5L2503 at it's known I2C addresses.
The VDDOUT1 and VDDOUT2 voltages measure 1.87 VDC at TP7 and TP8.
Properties of the SCL/SDA
Look at the manual for the evaluation kit:
MicroClock 5X2503 / 5L2503 Family Evaluation Board User Manual