We were just required to update our SSL certificate after the first year's expiration date come up. We've done this several times before with no issues—Google the right flags to use with openssl, plug that into Comodo, upload the certs and we're good to go.
This time we ran into all sorts of problems; our (outdated) macOS Servers kept kicking back our certs as invalid. This could very well be a problem on the macOS side, as these are years out of date and I wouldn't be surprised if they don't have to code to talk updated encryption techniques. But we also had a problem with our mail server: it's working with the cert we requested from the CSR generator at https://www.digicert.com/easy-csr/openssl.htm, but it lost the identity information: name of company, city state country.
Appears to be a cosmetic problem, but important cosmetics. What might have caused this? We generated the CSR using OpenSSL 2.6.5 on macOS 10.14. (Yes, also a few years old, but we have good reasons to stick with Mojave.)