"One or more load/fixture/contact/connector associated entities may not be valid" is a common error after 'duplicating' a scenario with a small geometry change.
To day I duplicated a particularly complicated one, redefined the three affected connectors, and tried to remesh and rerun. I get the error. All the connectors and contact sets appear correctly. The error provides nothing useful to act on. My post about this has two parts.
1) Fundamental usability issues like this coupled with inscrutable error messages demonstrate a gross lack of usability testing by Solidworks developers. It is the number one reason that I have withdrawn all my standing requests for additional Solidworks tools at my company and am openly evaluating other analysis tools for the department that I manage.
2) Now what? I already tried deleting all the contacts and connectors from the new scenario and copy-and-pasting them from the original scenario (a tip from the VAR from when duplicated contacts went haywire). That did not help. Remaking the entire setup is very unappealing, with 25 connectors and 49 contact pairs buried inside the assembly.