Odyssey skins not available on the PBE

So basically, I wanted to have a legendary skin for my Kayn on the PBE for a very long time. Now when it finally is there, I can't buy it. As a matter of fact, I haven't been able to buy it ever since it came out weeks ago. Is this a bug, and if it is, does riot plan to fix it? Thanks in advance.

Best regards,

Swooosh.