I currently have two active vaults, one fairly new one with 14 dwellers and one that I have had since the release of Fallout Shelter. Sadly it is with the long standing vault that I am seeing this issue.
The game loads fine to the vault selection screen. I have my old vault selected and I click "Enter Vault" (it does not matter if I load it from the main screen or from the vault selection list, the results are the same).
The vault loads and I get the "Daily Report" pop-up which I clear. From that point on, it does not matter what I do, the game will allow me to play for about 45 seconds then it crashes to my phone's Home screen. If I go back into that Vault, I get the "Daily Report" pop-up again (which pretty much tells me everything reset) and I have about 45 seconds of play time before it crashes again.
I noticed that if I enter that Vault, then try to go back to the main screen right away, it also crashes the game immediately (without waiting the 45 seconds).
This does not happen on my other vault (I played for about 20 minutes until I started missing the cool items I had in my original vault) and it does not happen on a newly created vault (which I played for a few minutes, got bored and deleted).
This just started this morning (after playing this vault since about 3 days after the game came out) and I was able to play last night and successfully "log out" (I always make sure to go back to the Main screen before closing the game).
I have tried "unloading" the game (via the double-click Home button, swipe up) and have done a hard reset on the phone.
I am using an iPhone 5c, 32 GB, running iOS 9.02 (I upgraded weeks ago, so that isn't a new variable). I also am encountering the iOS 9 "Game Center" bug where the game freezes 10-15 seconds when trying to connect to Game Center, but when I played the smaller vault I got past that bug and the bigger vault still crashed at 45 seconds.
The game is version 1.2 (which I upgraded to the day it came out, so that isn't a new variable).
My vault is no where near maxed at 130 dwellers (which I recently reduced from 146 via creation of an "unarmed/vault suit only" rush-failure deathtrap - but the reduction was a few days ago, so that isn't a new variable).
I only have 9 dwellers in the wasteland (three of which are dead but it doesn't matter if I clear them and bring the others in, after the game crashes their numbers are all reset).
Like many other players, I have put a bit of money into the game (not a whole lot, no more than $10 if I recall) and obtained a few neat legendary dwellers and items, so deleting the vault is NOT an option. Any help or support on this would be greatly appreciated!