"MCC can’t open because it is offline."

“Halo: The Master Chief Collection can’t open because it is offline. The storage device might be missing or disconnected.”
Started getting this error after Halo: CE released, and can’t access the game without reinstalling the entire package. Seen this in a number of other threads elsewhere, so let’s get a fix!

Make sure and file a bug report about this on the Halo Support site: https://aka.ms/HaloSupport

Be sure to read over the known issues list first before reporting