When setting up a pipeline that combines two ARGB video sources using `glvideomixer` it will work as expected the first time is set to StatePlaying, however, if the pipeline status is set to Null then back to Playing, `glvideomixer` will produce an image containing just one of the video sources for ~20 seconds until it starts showing the expected mix of the two streams.


Using the regular `videomixer` or `compositor` element instead of `glvideomixer` works as expected.
`glvideomixer` does also have noticeable delay on Linux as described above but it will last for ~3s  instead of 20s.