Ok, so I just got off the phone with the client. We did some troubleshooting and were able to re-create the problem. After some investigation, I found that source-NAT was causing the issue. Not sure why, but it was causing clients to not receive an IP from the VC and causing them not to associate. Removed Source-NAT from the ACL and now it works fine.
Note: Source-NAT was used so the firewall didn't have to be changed and DID work at first. Not sure what caused it to stop.
Thanks for the help! If the problem comes up again, I will re-update.