about some Bugs( or Errors) of Target Manager

Vuforia SDK Version: 2.5 - Description with steps to reproduce: Here's some question about some Bugs( or Errors) of Target Manager, Vuforia. 1. certain target image keeps being deleted from the list of Target Manager without any action of user.  it means that the marker image has been deleted by itself, automatically, repeatedly(Same image) This problem appears very often nowadays. Those Target images's target numbers are : 800, 801, 711,713  2. Some Target images(random) become inactive without any action of user.   - But it's still active after it changes its status to 'inactive'.   - Some of them are inactive after its status changed to 'inactive'.  This problem appears from about 6 months ago.  We've changed all the markers to 'active' status last week because we didn't know what to do.   3. Recognition fail : AR browser can recognizes the marker but couldn't bring the contents.  Sometimes it works, next time doesn't. This symptom has been repeated irregularly. Data/wifi status was fine.  This is continuous problem.   - Development OS (Mac OS X, Windows, Linux): Mac OS X, Windows - Mobile OS and Version: android & ios all - Mobile Device Manufacturer and Model name: android & ios all - Do the Vuforia Sample Applications show the same behavior?: