Baxter,
Thanks for examining my diagram. I appreciate it.
I've swapped the 1A and 1B wires and moved the RX wire from the sensor to 1Y on the IC instead. Attached is an image based off your recommendations.
If you notice anything else amiss, please let me know.
Once my header wires have arrived, I'll construct the prototype and see if I can finally catch a break (pun intended)!
Nathan