I’ve purchased a number of monoprice panels over the years and never had an issue. If it is a bad panel then it’s probably just a fluke.
Speaking of fluke... do you have a cable tester? That should tell you right away what the issue is. Even a simple wire map tester would show you as you wiggle the panel around.
Also, some NICs and switches have built in testing capabilities. Maybe poke around your equipment and see which ones do. I think the intel NICs should.
Riley