I had an 11Day trial of Premium remaining, then I got 3Days Elite trial out of a Crate. Then after the 3Days of Elite (now), i have no more premium. Now 1 of my Backpack rows got deleated. I knew, that my Elite trial will end, and i sorted my backpack, with the thought in mind, that i would keep my Premium trial for 8 or 11 days... But NO the server is bugging again. Now 3 Flames, 1JP and 1Mini got deleated.
I'm sorry to tell you that it appears that getting a new trial got you rid of your old premium trial. Apparently we can't replace any of your items if you don't have any prove for the loss. If you happen to do so feel free to contact a senior about your problem on for example discord!