Retrieval of remote recordings stuck

We are implementing onvif profile S and G for our NVR in Milestone. When we try to retrieve edge recordings for a certain time, Milestone will correctly search for recordings and for the URI of the first recording. It will download some frames from our RTSP stream and then ask for a recording at a later time. This next timestamp is always between start and end time of our first recording (so the recording it should have already received). Then it will keep asking for this recording and get stuck in an infinite loop.

We are at a loss of what might be going on here. I added a WireShark trace of this behaviour. Any help is greatly appreciated.