i am a 1st time user and i set to milestones for a freelancer, the 1st one was easy i clicked on it and payment was made. i then recieved the 2nd milestone and i tried to do the same but it would not let me click on the 2nd Milestone. I then ended the contract thinking that this was the correct way to finish the job. the freelancer is still due payment.
Looks like you did not fund the second milestone.
Go to closed contract and pay via a bonus.
** Try not. Do! Or do not. There is no "try". ** (Yoda)
The freelancer doesn't have to accept the cancellation in this case. I see you have already paid a bonus and the total amount paid is the same as you set as your original budget.