No sure what’s going on or where to look for problems. The bind module page looks like the attached pic, but the zone files are still there and being loaded by bind.
This means Webmin is looking in the wrong place for the zone files. Usually this is because BIND is running in chroot and Webmin thinks it’s not, or vice versa.
What’s the path to the zone files? They’ll be in /var/named, somewhere, probably.