my son's twisty stick did the exact same thing, would be flying normal, then snap roll, looked back and the rudder was acting haywire.
Now being the person that I am, I simply took the stick apart, and placed a few drops of 3 in 1 oil on the micro switch where the twisty stick turns, and wouldn't you know, it fixed it
My sticks hat switches started to not work to the front right, took it apart and placed some 3 in 1 oil in the micro switch, and it now works fine.