opengl v-sync issue ( I can only get adaptive, not full ) ?

Hello, on windows7 using the wglSwapIntervalEXT function I use 1 (one) as the interval
in wglSwapIntervalEXT(interval);

This used to work ( and still does on AMD ) but I think I am getting adaptive synch instead of the
full v-sync that would prevent screen tearing at less than 60 fps.

Does anyone know why I am getting the adaptive v-sync instead of the full v-sync that caps on the refresh multiple of (60, 30, 20, 15 …)

Using the driver control panel I cannot even force ‘real’ v-sync on.

This all used to work before they introduces adaptive v-synch back in 2012.

Any ideas at all?