It is none of those. The whole traffic is stuck, sometimes a car moves ~1 m forwards or backwards, or a truck/car manages to get in the roundabout.
But the second option is may causing the issue, but I can't tell you that because everytime I approached, the whole traffic was already stuck. (an example referring ro the second picture: The Iveco managed to enter, because the car betweem it and the red Iveco (car transporter) reversed)