Unity 5 UI Text Glitch (illegible characters)

Can anybody explain this? Testing on (and screenshot from) Android 5.0.2, OnePlus One CyanogenOS.

Happens completely randomly.

This is the code that updates the topmost text label:

 void Update () {        
         if (!_pc.IsDead) {
             CurrentScoreValue.text = "" + PlayerStats.Score;
             HighscoreValue.text = "Highscore: " + PlayerStats.Highscore;
         }
         else if (_pc.IsDead)
         {
             PanelFailedMenu.SetActive(true);
             FailedScoreValue.text = "" + PlayerStats.Score;
         }
     }

The bottom-most text label is never updated.

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