(playing on steam)
After finishing my daily challenges, daily event battles, all of my daily story battles, a couple of elite story levels, some random skirmishes and a few random dungeons, I checked my current crest total before logging off and it was ZERO! (I had over 900 crests after my previous play session.)
I tried restarting the game, still zero. I tried rebooting and restarting, still zero. I then did a quick pvp to see if it would be stuck at zero, give me the 2 crests, or fix itself back to where it should be. It just gave me 2 crests.
I then tried loading the game on my ipad. It showed me at 2 crests. I did another quick pvp on my ipad and it moved me to 4 crests.
So all of my previously earned crests for the week are just GONE.