There is an on-going cPanel issue where cPanel > Email Deliverability will report issues regarding the Reverse DNS records on systems where this is configured correctly.
DKIM and SPF will be displayed as valid but you may see "There is no reverse DNS configured for the IP address (192.168.0.1) that the system uses to send this domain’s outgoing email."
This issue is caused by a timeout being reached when validating the Reverse DNS (PTR) records for a domain and can be intermittent on some systems.
Externally, the PTR records for the IP show correctly.
This issue is non-fatal and does not affect email delivery.
A workaround for this timeout errors has not yet been identified at this time.
However, the cPanel team has an internal case open for this and currently evaluating the issue.
We will notify customers when a solution has been found.