Unable to get SSL certificate with lets encrypt for new subdomain/virtual server

SYSTEM INFORMATION
OS type and version Ubuntu 20
Virtualmin version latest

I have requested previously certificate for other virtual servers/subdomains without any problem but now I am getting:
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator webroot, Installer None
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for mail.send.catalyzerinc.com
http-01 challenge for send.catalyzerinc.com
Using the webroot path /home/send.catalyzerinc.com/public_html for all unmatched domains.
Waiting for verification…
Challenge failed for domain mail.send.catalyzerinc.com
Challenge failed for domain send.catalyzerinc.com
http-01 challenge for mail.send.catalyzerinc.com
http-01 challenge for send.catalyzerinc.com
Cleaning up challenges
Some challenges have failed.
IMPORTANT NOTES:

Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator manual, Installer None
Obtaining a new certificate
Performing the following challenges:
dns-01 challenge for mail.send.catalyzerinc.com
dns-01 challenge for send.catalyzerinc.com
Running manual-auth-hook command: /etc/webmin/webmin/letsencrypt-dns.pl
Running manual-auth-hook command: /etc/webmin/webmin/letsencrypt-dns.pl
Waiting for verification…
Challenge failed for domain mail.send.catalyzerinc.com
Challenge failed for domain send.catalyzerinc.com
dns-01 challenge for mail.send.catalyzerinc.com
dns-01 challenge for send.catalyzerinc.com
Cleaning up challenges
Running manual-cleanup-hook command: /etc/webmin/webmin/letsencrypt-cleanup.pl
Running manual-cleanup-hook command: /etc/webmin/webmin/letsencrypt-cleanup.pl
Some challenges have failed.
IMPORTANT NOTES:

  • The following errors were reported by the server:

    Domain: mail.send.catalyzerinc.com
    Type: dns
    Detail: DNS problem: NXDOMAIN looking up TXT for
    _acme-challenge.mail.send.catalyzerinc.com - check that a DNS
    record exists for this domain

    Domain: send.catalyzerinc.com
    Type: dns
    Detail: DNS problem: NXDOMAIN looking up TXT for
    _acme-challenge.send.catalyzerinc.com - check that a DNS record
    exists for this domain

The solution was just to restart apache2 server, very wierd.