Agree with everyone above screw did not break, it came loose and fell out. Nothing wrong with the attachment system just needs some help. As suggested above Loctite on the threads of the screws will do the job. Link below this blue version is removable.

https://www.homedepot.com/pep/Loctit...728/100371826?


Since one screw is missing and will need to be replaced, when you go to the hardware store you might want to pick up a couple of these Nylon lock nuts as TiHabanero mentioned above. Link below is just a sample, you will need to get one that matches the threads on your screws. It looks like there is enough length on existing screw(s) they could just be added, but if not you could get the screws a 1/4" longer. Either Loctite or nylon lock nut should do the job, use both and you will have a redundant back-up.
https://www.homedepot.com/p/Everbilt...274148#overlay