Character Movement Not Working
The script looks fine and should work as is - the issue is elsewhere. Perhaps you're not possessing the pawn or possessing another one? Observe the debug filter - do the nodes update?
The jarring thing here is that you do not have a springarm. While it's not technically necessary, with a setup like this, it's likely to lead to some strange movement behaviour, like moving off-axis and I can't imagine moving backwards with this. It's hard to tell for sure, though; just a feeling seeing how this is 3rd person and the camera must be offset. You will need to at least disable Use Pawn Control Rotation on the camera to retain some sort of the control.
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