For some reason the animation track applies the last keyframes rotation to the entire animation I'm fairly new to unity so have I missed something in the manual that explains what I've done wrong
Not sure I completely understand the use case, but when animating translation or rotation on the root transform of an object with the Animation Track, it always updates both, even if you don't supplies keys for one. The reason for this is the animator always writes them as a pair, in order to accurately calculate correct root motion.
Now maybe there's something wrong with my installation or again I don't fully understand but with this particular track and others I've created there is no default rotation unless I set one however once I add one the issue is fixed thank you for the help