Can't seem to hide/disable SSID broadcast

> Model: R7900P|Nighthawk X6S Smart WiFi Router with MU-MIMO

   Is that accurate?  Firmware version?

> [...] I have tried checking the box, saving, then unchecking the box
> and saving all to no avail.

   There should be no need to reset the settings on a new router, but
you could try it.  It seems to help in some situations where the
displayed settings disagree with the actual behavior.  When that fails,
you could try different (older/newer) firmware versions.

   Visit http://netgear.com/support , put in your model number, and look
for Downloads.  Under Firmware and Software Downloads, find the kit(s).
Download the kit you want.  Read the "Release Notes" file for
instructions.  While you're in the neighborhood, fetching a copy of the
User Manual (under Documentation) might be worth the effort.

> Any ideas>

   Not really.  Broader Web search for similar complaints?  You've
verified that the client(s) can't see the SSID when the router is off,
and it re-appears when the router is powered on?