When upgraded to 500 pack it still didn't fix the issue after re-syncing. We had to remove the device and re-add.
User running PI 184.108.40.206 and has a 100 Eval LifeCycle license installed. He had 137 devices managed in routers and switches. About 24 devices are shown as Reachable but Unmanaged and still show that way after a Sync. Confirmed the proper SSH and SNMP credentials were specified.
Enabled traces and capture logs to troubleshoot.
2013-03-XX 11:XX:24,70X [http-XXX-31] INFO inventory - The device 24XXXX04 with IP
XX.X.XX.XX is in UNMANAGED state.
2013-03-XX 11:XX:24,70X [http-XXX-31] INFO inventory - The device 24XXXX04 received for
collection is in unmanaged or maintenance state
2013-03-XX 11:XX:50,35X [ICE Service[ 1]Thread: 14] INFO inventory - XX.X.XX.XX
24XXXX04 (IP: XX.X.XX.XX) will not have its features collected due to Precollection check failed
because: All licenses (100) consumed, need to add more licenses
Since we were over the device limit, tried deleting a few switches until we had enough available devices. Add the switch back and it came managed without a problem. Therefore, the issue was caused by the license limit being reached.