So this report never got responded to... but I have another example of this behavior which I believe is incorrect.

Game#14099037 - End of round 1, Turn 50 - after I played 8-12, my opponent should have been forced to pass a turn, and mark his train. This did not happen.

It appears that his turn was skipped over entirely (51). After that, I could only play the 8-10, and the game ended with each of us with one tile, and I won a net 5 points. However, if my opponent's train was marked in the previous move as per the rules, I could have also played my final tile (5-3), and won 13 points.

Once again, I will cite the rule “If a player passes the move due to not being able to play, their train becomes marked” – which should apply in this case, but it is not how the game behaves. The turn is skipped instead of forcing a pass and marking the train.