"BTC" buy orders for "SKULLCOIN" has been working.
You should get a notice of order matching, then you need to leave your "CounterWallet" open and logged -in to allow the BTCpay to finalize(you should get a notification of progress in wallet)

You can try buying "SKULLCOIN" with "XCP" (that is suppose to work better). I would need more info to track down the order and see if I can see what is wrong(pm me).