Are the screws the self-tapping screws which attach the mounting rail/hooks? It is a known problem: https://www.crazyguyonabike.com/doc/...id=321316&v=RN

It hit me on back-roller pro's. I replaced them with the regular screws as described in the linked article.

Judging by the Ortlieb spare parts, now they at least use the normal screws and nuts at the ends of the upper rail. Is this the case for your ones?