Are they 2017 or newer Metron SL's?

I absolutely love the Vision wheels since they were updated in 2017. They have the same aero profile but they lightened them up and upgraded the braking surface.

They are now the best braking set of carbon clinchers have tried. (10 year bike shop employee and life long rider)

I've only used the supplied pads for my 55SL's and 81SL's. Try adjusting them and cleaning the braking surface.