ui button doesn't work after pressing home button on iPhone

My scene has :
* canvas for 3 buttons . 1 for sound , 1 for play and 1 for leaderboard ( game center ).
* game object for game center link with a script . script is :

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Code (CSharp):

1. using UnityEngine;
2. using UnityEngine.SocialPlatforms.GameCenter;
3. using System.Collections;
4.  
5. public class gamecenterlink : MonoBehaviour {
6.  
7. public int highScore;
8.  
9.  
10. public string leaderboardName = "";
11. public string leaderboardID = "";
12.  
13. void Start ()
14. {
15. highScore = PlayerPrefs.GetInt ("highScore");
16.  
17. #ifUNITY_IPHONE
18. if (!Social.localUser.authenticated)
19. Authenticate();
20.  
21. #endif
22. }
23.  
24. private void NullMe(boolsuccess)
25. {
26.  
27. }
28.  
29. public void Authenticate()
30. {
31. #ifUNITY_IPHONE
32. Social.localUser.Authenticate(NullMe);
33. #endif
34. }
35.  
36.  
37. public void ReportScore(stringleaderboardID, longhighScore)
38. {
39. #ifUNITY_IPHONE
40. Social.ReportScore(highScore, leaderboardID, NullMe);
41. #endif
42. }
43.  
44.  
45.  
46. public void ShowLeaderboard()
47. {
48. #ifUNITY_IPHONE
49.  
50. ReportScore(leaderboardID,highScore);
51. Social.ShowLeaderboardUI();
52. #endif
53. }
54.  
55.  
56. }

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*I linked leaderboard button to this script's ShowLeaderboard() part .

when I start the game everything is normal . if I wanna see the leaderboard I return to this main scene . I click leaderboard button , game center opens and I can see everything. I can do that over and over .
But when I press home button on my iPhone , my game goes to background as you know . when I press my game's shortcut and call my game back ... ui button for leaderboard stops working . it's still clickable but it does nothing. game center doesn't opens anymore. anyone can help ? I tried ui change , button change , game center script change. all the same .
testing phone is iPhone 4 8gb . iOS 7 . thanks .

 

Oh, I met the same issue. I test my game on iPhone5S and iOS simulator. Maybe it's a bug of Unity?

 

Yes this is probably a Unity issue. because it works fine on Unity 5.1.0 version

 

This issue is occurred not only game center but also all ios native dialogue.

 

Hope the issue will be fixed on Unity 5.2.