Pipeline's childs does not go to the pipeline state.

[Kseniia Vasilchuk]

Hi!
I am making RTSP server application. I've created two streams with appsrc, one for video and one for metadata, and I am trying to add seek feature.
But I have a preroll problem with metadata stream. I have a situation, when the seek event is coming, but there is no metadata to push now (maybe it will come later).
As sink needs at least one buffer to preroll and there are no ones, the seek is failing by timeout (because of RTSP). So I've tried to push one empty buffer to my appsrc.
I thought that I can check the current state of my appsrc, and if it is in PAUSED, just push the buffer to force preroll. But appsrc does not go to the PAUSED state after seek event even if pipeline went to PAUSED (I caught GST_MESSAGE_STATE_CHANGED on bus to be sure).
So, the question is: Is it ok, that the pipeline's childs does not go to the pipeline state?
Any suggestion, how preroll should be forced if we have no data for now?

Thanks!