Pymavlink 2.0.3 connection issue

Since I upgraded to pymavlink 2.0.3, tower does not bind the port anymore on connection. when I launch tower tcp:127.0.0.1:5760 it just loops 'waiting for connection...' After some hours of investigation I downgraded to pymavlink 1.1.73 and all worked again. Can you help me with resolving the compatibility issue please?
