@Andru123
See if toggling the Volume Mode during playback of the AC3 content works for you. This is the method/workaround I use on my 4660.
1. Launch Roku Media Player (RMP) and select the video.
2. Once the content begins playing, press the asterick (*) button on the Roku remote and under the Volume Mode on left side 'options' overlay, try toggling to Off. (then go back to using preferred Leveling or Night mode).
Annoying, but works for me.
Roku Community Streaming Expert
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