I´ve tested that today on et9000 with play, pause, standby, run =>
You are right, the movie runs and the screen shows the pause state.
But on et9000 the sound is there
So playing movie and showing pause after going to standby and going on is an openpli bug.
But the no sound problem seems not be an openpli bug
Just tested on the Solo2:
Play -> Pause -> Standby -> Switch on -> Video plays with sound but the pause button is displayed
Play -> Standby -> Switch on -> Video plays but no sound
Remember that resuming playback very often (but not always) results in no sound on all VU's. The 'solution' is to skip-back 15 seconds.