How to fix an error in installing secondary NS DNS: Cannot determine if the following servers are recursive nameservers or not?

Question

Domain Name System

Registered additional NS addresses for the site through Сloudns.net.
When I added only 3 extra. addresses to the registrar and in Domain names - My domain - Settings and Records (I use ISP manager Lite 5.182.3, BIND 9.9.4-72.el7 ) when checking in https://zonemaster.net there were no comments.

When I registered 4 more addresses and their IPs, when checking in Zonemaster, a warning appeared:
NAMESERVER WARNING Cannot determine if the following servers are recursive nameservers or not: (all NS names are listed with their IP4 and IP6, including the primary NS address located on my server via ISP manager).

How to fix?

Answer 1

Sent a letter to those. cloudns.net support. Corrected something on their own. Corrected.