A couple of days ago I used the steam wallet to purchase Zen in-game (I have STO as a Steam download). No big deal, I've done it before, click 'yes' when required.
However, for the last 2 days I have not been able to do so (to purchase the odd key). I click the 'Buy Zen' button in the in-game C-Store, select the amount I want, then wait. It looks like it's about to load the Steam window to allow me to authorise the transaction, then suddenly stops and gives me the message 'Your purchase failed for an unknown reason'.
Has anyone else had experience of this? If so, how did you fix it (if you managed to)?
I should point out that the overlay is enabled (I can Shift+Tab to it) and my Steam Wallet does have the amount of money loaded into it to pay for the transaction.