Apple updates aren't synchronized with SCCM.
However, there are no errors in wsus_publisher.log
Updates category isn't enabled in Software updates classifications:
Please enable Updates category in Software update Classifications.
1. Go to SCCM Console → Administration → Site configuration → Sites and select the primary site;
2. On the Home tab click Settings → Configure Site Components → Software Update Point:
3. Go to Classifications tab, enable Updates category and click OK:
4. Go to Software Library → Software Updates → All Software Updates and click Synchronize Software Updates:
5. Click Yes in the pop up window and wait for the synchronization to complete.
You may monitor its status in SCCM Console → Monitoring → Overview → System Status → Component Status → SMS_WSUS_SYNC_MANAGER: