Most of my champions have been removed from my account

I haven't played the game for a while and when I logged on I had on 2 star champions and only 5 of them. I used to have 5 stars but now they're all gone. Any idea on how I can get them back?
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Comments
Had you ever had multiple accounts ?
Was the last time you logged in, from a different device that now ?
Was it from logging in using GooglePlay or PlayCenter, instead of using an actual Kabam ID (or visa versa).