I have now run into this issue as well. I am a total OPNsense noob ... though I have a year of pfsense under my belt. I followed the documentation very carefully to configure Unbound and Dnsmasq to work together. I followed the example configuration steps in "DHCP4 with DNS Registration". "DHCP register firewall rules" has been checked since the beginning. After I was done, I noted that the Dnsmasq service failed to start. Logs pointed me to the issue. I disabled the ISC DHCP4 service and manually restarted the Dnsmasq Service. So far, so good. Then I noticed no rules had been created with respect to DNS on any of my interfaces. Based on this thread, I verified that the Dnsmasq General Tab listed all the interfaces (physical and VLAN) I had created (except WAN) in the "Interface" field, and under Advanced Mode the "Interface [no dhcp]" field says "Nothing selected". I did a System - Diagnostics - Packet Filter - Restart and when this changed nothing, I did a Power - Reboot. Can anyone offer any suggestions for things to check? Thanks.
POSTSCRIPT: Never mind. Noob GUI interface ignorance. I didn't realize all the autogenerated rules are collapsed into their own folder. The 3 "allow access to DHCP server" rules are on each interface.
POSTSCRIPT: Never mind. Noob GUI interface ignorance. I didn't realize all the autogenerated rules are collapsed into their own folder. The 3 "allow access to DHCP server" rules are on each interface.