Tim, it seems like Retevis did something odd with their initial firmware that turned on the TNC feature. I couldn't get WoAD working either but don't think it's a WoAD issue. I am fairly certain something is off in the radio/firmware. I covered it in this video
https://youtu.be/xs6RZ-jhtcg trying to warn other operators. WoAD keyed the radio just fine and initiated the connection but it is almost like the radio isn't pushing the received packets back to the app. I also tried it in Pat Winlink which didn't work either.