I've completed Return to Sender by choosing not to expose the Chief. I saved my game at two separate paths in-game. The NCR Eureka! path and the Yes Man No Gods No Masters path. My first playthrough was NCR, and his ending did not appear. I played again with the Independent (Both saves are from the same game.) ending and still didn't recieve the appropriate cutscene.
I've disabled all mods, which I'm very modest with the amount. A whopping 2 player made mods. (I know I'm boring ) One mod fixing the Sturdy Caravan Shotgun to apply perks and the other a terrain fix.
I've also installed/re-installed, defrag/verify steam tool, and extensive quest editing via console. (Just questresets, setstage, ect ect)
My question is how can I remedy this situation? It obviously works on other computers as videos exist of PC users getting this particular end game slide, but I've been hard pressed to find anyone with the same problem as me. It's really frustrating.