Well I don't know if this is the same but, I upgraded from and old server runnning 9.5 to new server running 9.5 sp2. Instead of updating all the agents on local machines, I copied the key and .crt files to the new server and had the DNS change to make the new server the old.
After that, the Windows Machines started reporting but the MAC's did not.
So after creating a new agent from the 9.5 SP2 server I installed it on a MAC and it still did not report to the core. I opened the landesk agent on the MAC and on the configuration tab, the ldms sever was <ldms server>.ad.<schooldomain.edu>.
Know this is the same setting on the agent from the old server for both the Windows and the Mac agent and all worked well on 9.5. I manually ran and invetory scan on the mac agent and it reported that it saved the file locally but could not connect to the server.
So on the configuration tab on the MAC I installed the new agent on, I took out the .ad and just have <ldms sever>.<schooldomian.edu>. Then a manually reran the inventory scan and it worked.
Now I am udating the Mac agent with that change and testing. I don't know if it is a DNS issue however, it worked on the old server with both the Mac agent and Windows agent having the same settings.