Email Search index is limited

My e-mail suddenly stopped returning full results when I search.  I've done some research and I think the Inbox needs to be re-indexed.  I have called into Comcast support and tried to get resolution through the technical chat, but no one seems to be able to resolve the problem.  I've had multiple tickets opened, but they are closed without resolution, and the technical teams refuse to escalate to the engineering team.  Does anyone know how to fix this - or how to get Comcast/Xfinity to fix it?