OPNsense Cannot Resolve Local Domains

[robbie11r1]

Hello, I am experiencing an odd issue with DNS on my OPNsense firewall itself where it is unable to properly resolve local domain names (configured using this setup, specifically Part 7 for local only: https://forum.opnsense.org/index.php?topic=23339.0. I notice this because I have a Nextcloud backup running nightly from OPNsense as well as a Github configuration change plugin running, both pointing at local domains (nc.mydomain.me and gitea.mydomain.me). I started to see failures in my OPNsense logs and that my backups had stopped, and when I went to investigate I discovered that my previously-working setup was no longer resolving the domain I had configured. To further investigate, I attempted to use the ping tool built into OPNsense and try to ping the ANY local domain on my network, and they are all unable to resolve *.mydomain.me addresses. Pinging using IP address works fine throughout this process, so I am confident that there are no firewall blocks and that this is a DNS issue. I have no issues using local domains from any other machine in my network.

I have my DNS setup with a very similar setup to what is posted here: https://forum.opnsense.org/index.php?topic=22162.msg146626#msg146626. I have Adguard Home listening on port 53, Unbound on 5353 and routing DNS over TLS via a Wireguard network interface.

From any other machine in my network, I am able to resolve local domains without issue, but it appears that OPNsense itself is having trouble. The only resolution I have discovered is that if I add 127.0.0.1 to System -- Settings -- General, OPNsense is suddenly able to resolve local domains again... but this only lasts for a couple of days and then I start seeing my backups failing. If I go back into System -- Settings -- General and click "save", everything starts working again...

I have firewall rules in place to redirect DNS queries back to the interface itself, but I don't believe that has any impact on OPNsense itself being unable to resolve local domains.

My /etc/resolv.conf is setup as follows:
domain localdomain
nameserver 127.0.0.1
nameserver 127.0.0.1
search localdomain

I saw a similar post here: https://forum.opnsense.org/index.php?topic=32656.15, but the resolution appeared to be that Adguard Home was not listening on all interfaces. In my case, it already is.

I am quite baffled and not sure where to continue investigating with this intermittent issue. Only other thing I can think of is that maybe I need to add a Cron job to "Reload system DNS resolver config", since it looks like simply going into my System -- Settings -- General and clicking "save" provides temporary relief... is this a valid thing I should be doing and if so, why?

Any help or directions to look would be greatly appreciated!