So, apparently, if I beat the game, I can't access my weapons, phone internet or missions. Whenever I try to access them, it kicks me out of the menu and my HUD dissapears. This means, no health, no map and I can't pull up my phone once this happens. This means, I can't do anything correctly after I beat the game.
I went back to a previous save (4 hours lost) and beat the game again, but this time, trying a different ending (End C first then tried Ending A). Unfortunately, this came up with the exact same results. While using my previous save, I was able to use my phone internet and weapons. I was able to use the phone, all the way to the last controllable moment you have with Trevor.
If anyone has any suggestions, please message me or respond.