Sorry for the delay, but I was able to spin up a new instance and use this flag. Also had two more cert requests today, all 3 checkout fine with that flag attached. Good News! Only follow up question is does certbot accept --preferred-chain "ISRG Root X1" in the renew action, or do i need to reissue the other 198? I only ask b/c this flag is not in the --help output.
Also if simple. Since i was getting the ISRG Root X1 on all of my certs b/c i upgraded a while ago when asked, why would they fail to validate?