But my screenshot is the same as your "16:9 broadcast with 16:9 source" screenhot, not as your first screenshot "4:3 broadcast with 16:9 source". Compare the black color on your first screenshot and on my screenhot. That channel is broadcasting in 16:9 all the time.
Edit: OK, it's working strange, sometimes it's working good:
- disable option "Keep AR (VMR)"
- change AR in the main window to 16:9
- enable option "Keep AR (VMR)"
- switch to TV window
- change AR in TV window to 16:9
= now it's working good, but the 4:3 channels are incorrect (in the main window - the AR of the main window is 4:3, channel AR is 4:3, so perhpaps it's even a bug??)
- disable option "Keep AR (VMR)"
- change AR in the main window to 4:3
- enable option "Keep AR (VMR)"
- switch to TV window
- change AR in TV window to 16:9
= result is the small 16:9 picture in larger 16:9 window, I think this might be considered as a bug
Try the steps above, you should get the same result as me.
Again, my suggestion is not just change to correct AR, but also change the AR of the window, that's all.