call me Cáitín
If a DT hub spins correctly off the bike then binds up when you tighten the thru axle, you have forced the 2 ratchets to bind together.Surprise, when through axle tightened, no free wheeling. If cranks stop, wheel turns a few degrees as chain goes slack.
Is there a spacer in there ? Make sure its on the right side when reassembling or remove it completely. Something is pushing the ratchets together.