Lumia 950 XL Unlocked Variant UK, non insider running 10586.29. The firmware update package doesn't appear to be available yet. Using WDRT, it shows the available firmware version is the same as what's installed on my device currently, even the software (OS) version available is a couple of revisions behind on the server (likely 10586.0/11). Unless WDRT shows it available you won't be getting any Windows Update notification yet, no matter how many times you smash that "Check for updates" button.
I certainly wouldn't hard reset, just be patient.
Just for reference, WDRT makes web requests to the following locations:
api.swrepository.com
softwarerepo.blob.core.windows.net
If the firmware package isn't on Microsoft's servers, don't expect an update notification coming just yet.