Help with stuck item

[Imanol]

Need help, I used to play TF2 some 7 years ago, I used scrap.tf like any normal player would, the thing is that I lost my PC and couldn't get one until last week, now I wanna start trading again but I left some items on my onsite inventory and I can't get them out, it says "preparing your trade, you're up next" but never gets past that, the items arent really valuable but it won't let me trade anything else until I get them out, any help or advice?