Alberto,
I don't have a compass plane, although I am planning to get one. However, from flat plane experience there are a couple of possibilites that come to mind.
We call the opening in the sole the mouth, not the cleft. I doubt this is the problem unless you have an adjustable frog on this plane which I cannot tell from the pictures (the frog is the angled piece on which the blade is bedded and on flat bench planes it can be adjusted forward and backwards which does vary the mouth opening, or at least it moves the edge of the blade towards or away from the front of the mouth). Usually the mouth opening will be sized to accomodate the thickest shaving you want to take during any particular planing operation and on a plane like this I would not expect it to be more than 1mm.
In your case I wonder if you are planing end grain or long grain? Is you problem confined to a particular radius or does it happen when the plane is set up flat, convex or concave? Dust is any case usually the result of a blunt blade, especially on end grain.
Possibly your chipbreaker is set too close to the edge of your blade and it is in fact blocking the mouth of the plane? If this were the case, I guess even a sharp blade might not be able to produce a shaving but only dust. If a chip breaker is not secured firmly to the blade, they can shift whilst raising or lowering the blade with the adjuster. I have had this happen on occasions when I have been a bit careless in setting up my planes.
As my comments might tell you, I am not speaking from direct experience with one of these planes. I might be ablt to advise you better next week!