GTM health monitor for Standalone Server not being sent

I'm trying to setup a standalone server in new GTM implementation and the health monitors don't seem to be working as expected. I've done the following tasks: - Created a new datacenter (which is showing green/available) - Created a new server as the GTM devices using the floating ip for the external vlan. (showing green / available) - Created another new server (Generic Host) with the ip of the webserver and created a virtual server with the same ip and the http health monitor. (showing red / down)

I'm able to successfully curl the webserver from the cli of the GTM device, so I know routing and network connectivity are good. I've done some tcpdumps and the GTM device isn't sending any traffic to the virtual server.

Can someone give me some pointers?

Thanks in advance.