There is currently a bug with making the first hit against a monster or player (as shown below). Your first hit won't register any damage but will show the xp.
This will be a huge issue for staking as you could entirely miss out on a spec and it may even lose your pid win. No refunds are to be given through staking now that this thread has been made and you have all been warned.
Hopefully it will be fixed within the next update
Edit:
Palidino is now aware of the issue and is working on a fix.