No CAA record on oracle.com (wildcard=false) contains the issuance domain "letsencrypt.org". You must either add an additional record to include "letsencrypt.org" or remove every existing CAA record. A list of the CAA records are provided in the details.
oracle.com. 0 IN CAA 0 issue "symantec.com"
oracle.com. 0 IN CAA 0 issue "digicert.com"
CAA records control authorization for certificate authorities to issue certificates for a domain
oracle.com. 0 IN CAA 0 issue "symantec.com"
oracle.com. 0 IN CAA 0 issue "digicert.com"
A and AAAA records found for this domain
oracle.com. 0 IN A 137.254.120.50
The IANA public suffix is the TLD of the Registered Domain
The TLD for oracle.com is: com
The current status.io status for Let's Encrypt
Operational