@bearhntr
That's basically a Proxmox Topic. Maybe its firewall only allow access to the former interface.
As I understand it - in order for any other VMs (currently only pfSense on here - until I figure this out) need to use the same vmbrXX that pfSense is using for LAN in order to get an address? Is this accurate?
Yes, if you set an IP on the bridge, I'd expect, that you can access the GUI using it.
However, to have IPs on multiple interfaces within the same subnet, is not a good idea at all. So you should remove the other and maybe it needs to be rebooted then.