pfSense

After an upgrade from 2.5.2 to 2.6.0 we have been encountering an issue with network booting. Under inside the DHCP network configuration file, there is a configuration option that didn't exist before. That is preventing out networking booting from working properly

subnet 192.168.240.0 netmask 255.255.252.0 {
    pool {
        option domain-name-servers 192.168.243.254;
        deny dynamic bootp clients;
        failover peer "dhcp_lan";

        filename "legacy.donotuse"; << it seems that this option is causing network booting to fail. 
        range 192.168.240.80 192.168.243.249;
    }

    option routers 192.168.243.254;
    option domain-name-servers 192.168.243.254;
    default-lease-time 14400;
    ping-check true;

    next-server 192.168.243.132;
    if option arch = 00:06 {
        filename "legacy.donotuse";
    } else if option arch = 00:07 {
        filename "/grubnetx64.efi";
    } else if option arch = 00:09 {
        filename "/grubnetx64.efi";
    } else {
        filename "legacy.donotuse";
    }

The line in the pool configuration is overriding the if statements later in the configuration file.

I have tried to unset network booting, which will remove the line, but when I re-enable network booting it will add the line back in. I can't find an option where to update that filename.