FGT Captive Portal issues to FortiAuthenticator

[nuGeorge]

Hi guys, I'm not sure whether to post this here or the FortiAuthenticator thread but I'll start with here. 

I'm trying to get captive portal working via the interface and SSID on my FGT, however I'm running into some issues. I have a FortiAuthenticator that is set up with SAML to connect to G Suite for authentication, and this part is working fine, however when I try to use the Captive Portal and point the Authentication Portal to the SAML portal address (which is my FAC) it appends a bunch of extra html to the end of the url:

?login&post=http://192.168.5.254:1000/fgtauth&magic=05040326464b&usermac=00:e0:4c:68:03:9f&apmac=e8:1c:ba:f1:83:c2&apip=192.168.5.254&userip=192.168.5.129&ssid=dmz&apname=FortiWiFi-60E&bssid=00:00:00:00:00:00

and fails. I've also configured Guest Smart Profiles to roll out certificates to users who join a specific SSID, however when I use Captive Portal for this it does the same thing as above and fails to connect. I'm able to hit the FortiGate disclaimer page, but once I accept that it appends the above stuff and fails to connect.