I had a similar issue with DHCP, after taking a look at the logs it appeared that the wrong group policy was being applied to the anyconnect config I had in place. I have clientless SSL VPN setup, and the anyconnect profile was using the SSL VPN group policy I had configured, which didn't have a pool assigned to it because it wasn't necessary for the clientless vpn access. As soon as a added a pool to that group policy, the anyconnect clients got IP addresses. It may be that the group policy you think is being applied to your ssl vpn client profile is not the one actually being applied, it may be the default that has no pool assigned to it.
