Delegating your domain to Cloudflare in this way does not work. Pointing a domain name to different nameservers should be done through a nameserver setting option, it’s not done by creating NS records in the nameservers you are currently using.
Because this setup is “wrong” it seems that some DNS clients will use the A record you have setup at CloudNS and some do go through Cloudflare.
I think that if you want to use this domain, you’re probably stuck with CloudNS’ nameservers, and you can’t use Cloudflare. So I would suggest to remove the NS records from your domain and just use CloudNS’ DNS management to avoid any strange issues.