I was upgrading a Lifesteal Epic shielf on a lvl 40 Herald when I notices it was taking silver at 400 a pop but not upgrading it as it said it was. Lost about 200 K in silver and shield is still at 0. I can upgrade other stuff but not that.
Sometimes a bug happens on client side with upgrading animations. Please clear the app cache and restart the game, it should fix the issue. Either the silver will be reverted back or the item will be upgraded.