I read in a few places. 1. It could be the actual sanding paper discs. 2. Its the new pad you bought. And you need to lift the hooks up. As I described in my last post. 3. Never store your sander if it has hook and loop without sandpaper attached. It will flatten the hooks. 4. Dust around hooks act as a lubricant blow off disc. If its caked wire brush then blow off. Worst case senareo wash in hot soapy water then blow off with air hose. 5. Take a soft brisal brush and rub the back of sandpaper discs to raise material fibers.
Sorry buddy your having trouble. I have always used PSA that way I never had any trouble. Plus PSA is cheaper. It can get real cheap if you buy sheet sandpaper and cut out your discs from the circle tracings and spray adhesive on the back.
Good luck and letbus know if any of these suggestions helped.

Jeff Vandenberg aka "Woodsconsin"