We credited your account and also put some extra sats as a bounty for reporting this bug. It's been fixed and it'll be deployed tomorrow morning. 

I think there's a bug in pay from internal wallet. We will work on fixing it. Meanwhile, we'll credit your Predyx wallet.

I'm not sure what a hard refresh is, but I turned it off and on again and the balance didn't reset.

Undisciplined

Also, can you hard refresh your browser and see if the balance is still decreased?