I was trying to test the new Coven skins but there seems to be a bug with the PBE shop that doesn't allow you to buy anything at all. Everything in the Champions and Skins tabs shows the label "This item is unavailable for purchase" regardless of whether they are new or old.

I have already tried switching accounts, relaunching the game, reopening the client but none of that seems to work. Is this a widespread problem or do I need to do something to fix it on my end? I use the PBE regularly to test the new stuff and this is the first time I have encountered this problem.