DHCP Not Working with VLANs Enabled

[jrob630]

I have tested this on official Netgate hardware as well as VMs running in Proxmox.

Happy to provide config files/printouts from my lab.

Background:
Running a HA setup with same hardware.
2 VLANs - Data and Guest Networks.
Interfaces are configured exactly the same on both instances. WAN, LAN, DATA (VLAN), GUEST (VLAN).
XMLRPC and State Sync are working without issue.
CARP addresses are configured for each interface and set as the gateway and primary dns server.

Interfaces:
WAN: em0
LAN: em1 - 172.16.10.0/24 CARP - 172.16.10.254
SYNC: em2 - 172.16.20.0/29
DATA: VLAN10 on em1 - 192.168.10.0/24 CARP - 192.168.10.254
Guest: VLAN20 on em1 - 192.168.20.0/24 CARP- 192.168.20.254

The Issue:
DHCP refuses to start when VLAN interfaces are enabled.
(Error in DHCP Logs - Interface em1 matches multiple shared networks)
As soon as I disable VLANs, DHCP starts and runs without issue on the LAN/em1 interface.
DHCP Fails to start on the VLANs, even if DHCP is disabled on LAN interface to begin with.
I can assign a static IP on either of the VLANs and route out without issue.

A few things I've tried:
Compared config.xml and am not seeing any zombie addresses or addresses that are somehow overlapped between interfaces.

Really appears to be a bug or something. I've combed through and double, triple checked these settings for probably a total of 20+ hours without luck... Google hasn't provided anything specific to the issue I'm having. Again, both on official netgate hardware as well as VMs.

I'm at a loss for words or things to try at this point.

Greatly appreciate any help with this.