Since last week it could be possible that you experience an issue with the POST shipping-label. The process status of this call stay in pending and then ended in failure or timeout.
We are working on a solution.
Update 13:45:
There where two reasons this issue could happen, one is resolved.
Another reason this issue can happen is because the shippinglabel is not available yet. This is because we are prevent for to early handover to the transporter. In the v8 POST deliveryoptions we have created the attribute: earliestHandoverDateTime for when the label is available.
We are currently working on a solution to prevent the process status go to timeout but to failure with errormessage