Users not getting IP while connecting to one of the SSID

[scopeproperties]

2 of our sites few users are not getting IP address from one of the SSID however they can connect to another SSID.

we have 3 SSIDs in our fortigate with seperate VLAN in bridge mode and DHCP is also on Fortigate VLAN. it happens randomly with random users they can connect to guest SSID however 1 or 2 users when they connect corporate SSID they #don't get IP from Fortigateand shows no internet.

We did Forget SSID and try, we did laptop level troubleshooting as well. DHCP lease IPs are availabe more than 100 free. 

[AEK]

Check the WiFi events under menu Log & Report > Events. You should find what is happening from FGT/FAP/SSID side.

Also check in Windows events for anything relevant.