I've used either USB port for Sentry Mode and they both worked fine in our 2019 S. It shouldn't matter which "universal" serial bus port to use, is my expectation. What does matter is the quality of your flash memory card. SD cards/microSD from Samsung and Sandisk all failed me within a few months, and even had a Sandisk USB SD card reader fail. Once I switched to an SSD then no problems for 9 months so far, using either USB port.