bind 9.14.2 query fail for vpn.deltaww.com

I have a question about bind 9.14.2. The bind version installed by dns server is 9.14.2, and the user will not succeed in dig vpn.deltaww.com.

The message on Log is as follows: query-errors: info: client @0x7f6f080c0ef0 xxx.xxx.xxx.xxx#58355 (vpn.deltaww.com): query failed (failure) for vpn.deltaww.com/IN/A at query.c:6786

If you reduce the bind version to 9.12.4-P1, you can succeed to query.

Is this the problem that the deltaww.com domain is not set correctly or is the bind version? Thank you for your response.