Intermittent PDK P1734 and P1732?

The car was throwing intermitting p1734 (one of the shift rod distance sensors' errors) and wouldn't go into reverse (while all forward gears still work). If I do a PDK recalibration it would work again, until some random time/miles later it will throw the same code and wouldn't reverse again (talking about possibly hundreds of miles of driving until it fails again).

Thought the sensor was on the verge of failing, had a shop to replace the sensor with t-design unit, 200+ miles later it threw a p1732, and was stuck in the forward gear it was in. Power down the car and restart got it to drive again (with CEL still there) but in a short amount of time error came back again, restarting the car again managed to get it driving normally (with CEL), and managed to get home.

For now, I have cleared the code, reprogrammed the TCU (previously I only recalibrated PDK but didn't reprogram the TCU - I have heard people seeing weird behavior in recalibration which was fixed by reprogramming the TCU so I thought it wouldn't hurt to try), recalibrated the PDK again, drove a few miles yesterday seems to be good for now. But I suspect it will come back up at some point. Looking for ideas/inputs on what could cause it to have shift-rod sensor errors so randomly.

I thought about several possible other causes:
1. Battery - battery is 4.5yr old but is in good shape - overnight still got 12.5v so I can probably rule out a battery problem.
2. Harness/wiring connection issue, although it's somewhat hard to imagine it behaves so randomly, and also the error never pops up over driving over bumps and stuff but always when starting the car/driving smoothly. The shop replaced the distance sensor and saw the distance sensor harness and it looked ok. With the TCU harness/connection, checking it involves pulling multiple interior trims I'm not sure if I can DIY that, I could try to find a shop to do it but obviously don't want to unless I have a reasonable degree of confidence that it might be a possible cause.
3. TCU itself - again I have a hard time imagining it only fails randomly if the TCU is faulty
4. The shop did the sensor replacement floated the idea of maybe the new sensor was bad out of the box, but to think the new sensor is bad out of the box, also behave in a similar way before sensor replacement (error only so randomly / intermittently) makes it think it's unlikely to still the sensor problem but more likely to be something else.

Any thoughts/suggestions?