I have a 60D, a couple of FSW 108 on 6.0.1 using fortilink and a FAP 221C on 6.0.2
Had to downgrade again to 6.0.2 as the FAP couldn't get a DHCP address (DHCP server on FG, same vlan/subnet)
I was seeing discover/offers but no request then the AP would default to 192.168.1.2, tried reset, reboot, moving to another switch etc. but always the same, downgraded and back to normal.
Other DHCP clients were having no problems getting addresses.
Fortinet Expert partner - Norway