Thank you came here troubleshooting the same issue, seemed to really happen more when it was dusty/dirty.an update, for anyone w/ a similar issue...
I tried to locate the source of the creak more precisely by pushing against different parts of the shock and mounting points, while compressing the shock. Still had the noise.
Then I rotated the spring 10 or 20 millimeters - voila! No noise. So I guess the spring was seated funny (very little preload on it), and was rubbing on something.
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