OK still having the same problem but now I'm using a workaround. From iTunes on my PC, I select Apple TV from the speaker list, (via the icon that has a triangle within a rectangle) then start the playlist from there. The podcasts start playing and can then be controlled, e.g. paused, from the Remote app on my iPad. Also on the iPad in the list view up at the top it shows the upcoming podcasts and they are in the right order. It would be nice if Apple fixed this so that the podcast playlist could be started from the iPad instead of having to start it from the PC.