Confused - Arrow spine weirdness

Hi, perhaps someone can unravel this. Compound bow set at 45lbs, 32" long 550 spine Skylon Paragon arrows with 120gr points. 3 x fletched arrows and 2 x bare shaft arrows. Paper tuning gives bullet holes. Bare shaft tuning the arrows land together at 10m. At 20m the bare shafts land well left of the fletched arrows, at 30m the bare shafts miss the target to the left. Fletched arrows all landing accurately. Bare shafts landing left means the spine too stiff as per Easton tuning manual...

Confused - Arrow spine weirdness