I think that a/v sync issues are caused by the lateframe patch. In my latest build I only increased a limit in Kodi - this fixes frame jumping in my test samples:
LibreELEC.tv/kodi-le-030-lateframes.patch at d3763339ea877854e635bf7c00f46fb8d2ab87e1 · kszaq/LibreELEC.tv · GitHub
Skipping 'late frames' is very drastic solution to achieve video/audio sync causing video playback stuttering. This procedure have to be for freerun mode totally relaxed. We have to find another way how to reach av sync. In current stage simple workaround is to use timeshift. Shifting playback few seconds back will reach perfect av sync without any drops and skips.