That is strange that the write operation would work while the read operation would not.
Is it possible that the voltage levels would make a difference? I'm not an electronics person, but I think I have noticed that some I2C devices are 3.3V and some are 5V and some will dynamically adjust.
The roboRIO is labeled for 3.3V on the I2C power and from the website (
http://www.modernroboticsinc.com/color-sensor) it looks like the sensor is expecting 5V on the power line (the website doesn't say that it won't work on 3.3V, but I didn't see anything saying that it would either).
Does the Raspberry PI that the sensor worked on have a 3.3V I2C bus like the roboRIO or a 5V I2C bus?
Not sure how this might impact things or if it could explain why you can send data to the sensor but not get anything back, but maybe it is something to consider or to ask the manufacturer of the sensor.
I have seen ads for items designed to convert between 3.3V and 5V I2C lines (
https://www.adafruit.com/products/757). Have never tried using one though.
Good Luck.