I completed Apprentice 40 to Apprentice 1, but when I went to open golden card pack game stopped moving, I wait a little bit, after i closed the game, and reopened it, it disappeared and i have screenshot and videos prove
If you look at your card collection, you will probably see that you have 5 golden cards that you did not have before.
When you open a pack, the second you drag the pack to the screen the contents are added to your inventory. All the animations and you clicking on the five cards to reveal them is just visual effects. If anything (disconnect, client freezing, server crashing, etc etc) happens after you drag the pack to the middle of the screen, then you might miss out on the animated revelation of what was added to your account, but it is still added to your account nonetheless.