Could it be possible that GSX is not disconnecting from rudder control and it remains even after I am cleared?
GSX sets the rudder to the exact same heading your airplane was facing at the end of the pushback, then it release its control over it. The rudder is not controlled separately so, if GSX wasn't releasing the rudder, you wouldn't be able to control the whole airplane.
Since nobody else has ever reported this problem and surely not for other airplanes, it might be possible the Airbus X uses an internal simulation of the rudder control, similar to the Majestic Q400, which uses its own flight model, so there are problems at the end of the pushback, because the two simulations gets out of sync.
To handle the Majestic Q400, we added a variable in GSX that airplane developers can read to know if GSX it's pushing back so, if it's certain that this is indeed the problem, perhaps Aerosoft can patch the Airbus X to read such variable and stop updating its own internal simulation of the rudder (assuming there is one) while the variable is set to indicate GSX is pushing, same as the Majestic Q400 developers are doing to be compatible with GSX pushback.