Could you try this?

Modify the test code to print out the "Response" value coming back from the controller.
E.g HEROUT [HEX2 Addr, " ", HEX2 Response, 13, 10]

Then this?
I2Cwrite SDA, SCL, $68, [$1b, "[", 1, ";", 1, "H"]
I2Cwrite SDA, SCL, ["hello"]