dns zone - Conflict with CNAME wildcard with child CNAME

I migrated from PowerDNS to Knot 2.7.

I have a conflict with 2 DNS records now.

abcd.**www**.example.com CNAME -> somehost.example.net
*.example.com -> example.com

Now the problem is with the www.example.com domain. In PowerDNS it was to resolve as *.example.com. Now there's no response. When I add A or CNAME record for www.example.com all is ok. Problem is based on first CNAME as I wrote above.

Can you explain me why and how can I fix it?

Thank you.