I am replying to a very old post with the hope that this might be helpful to someone like me who had this same exact issue.
So I had this similar issue with one my users who is connecting from Cisco AnyConnect client on Windows 10 computer.
[Windows 10 with AnyConnect] -> [ASA] -> [ISE] -> [AD]
After capturing the RADIUS packets by running debug on the ASA Firewall the issues was related to the username! The user was entering incorrect username!
The debug commands that I ran was:
debug radius session
debug radius decode
debug radius dynamic-authorization