Ok now, without falling into alcoholism, I have found a bottle and tried it out. No results.

I did small inspection, and there was idea, that maybe there is some glue issues between the leather and amorthisation stuff that is beneth ( I have Razor-Strop Streich-Riemen). So I just made a run of thin knife beneth to be sure that nothins is keeping the leather. No results.

Ok, the other idea is that it is some kind of deformation due to storage conditions? I have now put strop on flat table and put around 2-3 kgs (4-6 pounds) of pressure for night.

If it does not work, I will try writting to the shop. Returns would be complicated as I planned my trip to Grenoble in France the way I could jump into the shop in Paris