Have had similar on a 12 speed cassette, and it was what Eseman said. The smallest sprocket barely engages with the splines on the free hub so it's really easy to knock it out of place as you tighten the lock ring.
@Crumbs started
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Have had similar on a 12 speed cassette, and it was what Eseman said. The smallest sprocket barely engages with the splines on the free hub so it's really easy to knock it out of place as you tighten the lock ring.