When you generate the cert with certbot, it will give you a list of domains and assign a number to each potential subdomain. You the need to enter the numbers identifying the subdomains each certificate is to be issued for … so
So when generating the first certificate, you would enter: 3 4 which will generate a certificate for both subdomains. You will reference that certificate in your vHost file for that domain. You mentioned that you issued certificates for both domains - I am interpreting that to mean you issued 2 certificates. Your vHost file can only reference one certificate. I guess you chose the wrong certificate for these two vHost’s.
I suspect that you only entered 4 for the certificate that you are actually using.