Hi I started the game ~10 days ago. I have run into an odd issue. Artifacts are disappearing from my artifact storage. I am way under the 700 max amount. I am not selling any of them. 

3 very clear examples:

1) For the new player awards, I received a 6 piece life leech set. I had all 6 pieces and then a day or two later the Chest piece was gone. Not used on any player. Not sold. Just gone. I bought a few life leech items from the market, a few days later...the life leech 3star sword disappeared again. 

2) My second new player set that I am getting day by day now is retaliation set. I had recieved 4 pieces, and today when I tried to equip an hero with it, I saw the Boots (Received day 1) are gone. 

The first time this happened I figured I accidentally sold it. Since then I have been keeping a very close watch and many things have disappeared.

It is possible the other artifacts are disappearing as well but to be honest I am not tracking all of them because many of them are just garbage.

I am tracking only the important ones that I want to use and slowly they keep disappearing.

Is there any explanation for all of this?