I have encountered the same issue today. C172 Float (steam gauge variant).
Landed at a seaplane base with roughly 10kts headwind.
When I wanted to turn around to make it back to the docks, I could not for the life of me turn the aircraft around. Full rudder turned the aircraft roughly only 10-15 degrees to either side, before the aircraft hit a wall and bounced/got pushed back. Same into the other direction.
In the end I had to use slew mode to get back to the docks.