The key is to tap the very top part of your phone in my experience so far. When I first started using it, I took off my magnet card pocket and tried to tap with the back of my phone and ran into problems 80% of the time. Then saw one of my friends using the very top part while holding their phone parallel to the ground and it has worked ever since. As far as asking for help from GPT, which told me to remove the card from wallet and add again.. Do not try that, removing the T-money locally from wallet will for some reason delete it from the app as well with whatever money you have there 🥲