Unable to access GUI from different subnet

Hoping someone can advise where I'm going wrong.

I have deployed a pair of 600F's in HA with a Cisco 9300 core switch. Firewalls are in a FW mgmt VLAN 99, IP 10.100.99.0/24.

The firewall mgmt interface on VLAN 99 is 10.100.99.253

When on the same VLAN I can access the gui no problem as expected. But we have a server VLAN 50, 10.100.50.0/24, where we have installed CRT for switch management, and the management server in 10.100.50.81 is unable to access the GUI at 10.100.99.254.

I have enabled HTTPS and SSH on the mgmt interface. There are no ACLs on the core switch and no security policies that seem to be blocking access.

I read a post regarding local-in policies so created one for the mgmt interface to allow VLAN 50 but nothing.

It's a very basic setup and I'm not sure what's up.

Ive installed only 1 fortinet before so newish to them, so it's odds on it's me

Thanks