Can't buy 5 star sig stones from bg store.

As the title says, I am unable to buy 5star sig stones from the battlegroubds shop. Whenever I try, it says that an unknown error has occurred.

Comments

Try and clear cache of the game?
If it persists, contact support.

The store is probably bugged, there was another dude that couldn't buy 6* shards and he was getting the same message

Clearing cache didnt work, sent a support ticket.

Shame, wanted to sig up iceman today, seems itll have to wait a while.