There are situations where you will not get the extra days on your certificate.
Primarily this would be because of changes in the domain name ie. changing from mydomain.com to secure.mydomain.com
Please note that during the renewal process you will require a new CSR.
CSR generation instructions for your application can be found by searching "CSR generation" at https://support.sectigo.com/Com_KnowledgeMainPage
Extra days at renewal is not possible where the domain name changes.
If you have any questions please contact [email protected]