You seating due it's set up wrong way .you can't set up your seating die same way as your sizing die.
Put your case in the shell holder raise the arm and start turning your seating due till you feel the resistance. After back out the die 1 full turn and tighten it.
See if it works?
You have to put you brass in a shell holder and and lover the arm and the put you seating die in until you feel little resistance after back out the die 1 full turn
I had the same problém
i’m willing to make a wager that you are shooting with their muzzle brake Which wasn’t designed for 6.5 mm
Please take the muzzle brake off and you will the difference