So having recently comeback to the game due to the transfer, the processing costume for berserker that I had bought 2 years ago has gone missing. I can't find it anywhere on the accounts. Support don't reply. 

Same thing just happened to me with my kunoichi, several items from my ayo set have vanished and I can't make offers for the individual pieces through the tradehouse, probably coz the game still thinks I have them in my inventory

Please send a ticket with your issue, to make sure the GMs can assist you with that