The best I could tell was an upgrade back in Dec. 2019/Jan. 2020. It seems like it was a move from NSS to SSL for a number of pieces? Anyways, I'd had Ipsilon configured on the same server, and that move didn't make things happy as there was a port overlap. (Unsupported configuration, I know.) Lots of reconfiguration and copying certs around to get it straightened out.
Right now, everything starts on both servers. However, on the "secondary" that is not the renewal master, there's a number of "certificate doesn't match the CS.cfg" errors. 'ocspSigningCert cert-pki-ca' 'subsystemCert cert-pki-ca' 'Server-Cert cert-pki-ca' 'auditSigningCert cert-pki-ca'
Along with a: "msg": "Incorrect NSS trust for Server-Cert cert-pki-ca. Got ,, expected u,u,u",
The "primary", which is the renewal master listed on both boxes, shows none of those errors. At one point, I had figured out how to "force sync" the certs, but I've since forgotten.