Hello, I think there is a bug where it is not counting tiles in your own discard or hand when calculating the number of tiles that can improve a hand. For example it told me "you discarded X which results in 12 tiles that can improve your hand: 5m, 8m, 4s". However there was a 4s in my hand and a 4s in my discard which would be 10 possible tiles (4, 4, 2) not 12.
This also seems to lead to bugs where having 1s,9s as the only sou in hand will trigger a yellow warning if you discard either of them. Pitch the 1 and it will claim you get 1 more tile of efficiency with pitching the 9 and vice versa.