I had this same issue, in my case I'd upgraded the SMP install to SD 7.5 am still running a SD 7.1 SP2 server.
The SD7.1 server had this exact fault where the License Status Manager showed no licenses.
The only significant change I made was to use the Certificates mmc console on the SMP server to delete all my old expired license certificates. After this, restarting the SD server did NOT fix the issue immediately but it did go away over night.
I hope that helps someone.