As of right now, I am unable to run a single player Skirmish when running offline in Steam. Online, starting up a single player skirmish works fine. 

The log file error (in part) shows: 

Player 1: active(False), pending(True), gameLoaded(True), steamid(), tachyonid(00000000-0000-0000-0000-000000000000), name(), handicap(4), team(1)
Player 2: active(False), pending(True), gameLoaded(True), steamid(), tachyonid(00000000-0000-0000-0000-000000000000), name(), handicap(4), team(2)
Player 3: active(False), pending(True), gameLoaded(True), steamid(), tachyonid(00000000-0000-0000-0000-000000000000), name(), handicap(4), team(3)
Player 4: active(False), pending(True), gameLoaded(True), steamid(), tachyonid(00000000-0000-0000-0000-000000000000), name(), handicap(4), team(4)
Player 5: active(False), pending(True), gameLoaded(True), steamid(), tachyonid(00000000-0000-0000-0000-000000000000), name(), handicap(4), team(5)
Player 6: active(False), pending(True), gameLoaded(False), steamid(), tachyonid(00000000-0000-0000-0000-000000000000), name(), handicap(0), team(-1)
Player 7: active(False), pending(True), gameLoaded(False), steamid(), tachyonid(00000000-0000-0000-0000-000000000000), name(), handicap(0), team(-1)
Player 8: active(False), pending(True), gameLoaded(False), steamid(), tachyonid(00000000-0000-0000-0000-000000000000), name(), handicap(0), team(-1)
Player 9: active(False), pending(True), gameLoaded(False), steamid(), tachyonid(00000000-0000-0000-0000-000000000000), name(), handicap(0), team(-1)
-------------------------------------------------


------------------- Error ----------------------------
00:32 - NullReferenceException: Object reference not set to an instance of an object
LoadingManager.GenerateHintText ()
LoadingManager+<StartUpGameCoroutine>c__Iterator0.MoveNext ()
UnityEngine.SetupCoroutine.InvokeMoveNext (IEnumerator enumerator, IntPtr returnValueAddress)
UnityEngine.MonoBehaviour:StartCoroutine(IEnumerator)
LoadingManager:StartUpGame(Boolean)
AppMain:Start()

Thanks! And let me know if anything can be done. This has started sometime in the past 2 weeks.