I have the same issue on a cubox-i4pro.
With HDMI (directly to TV) I have audio stutter every couple of seconds like described above.
With SPDIF the sound is completely distorted. It is like the audio is sometimes being slowed down dramaticaly resulting in music in movies being completely off-key and voices sounding like they are under water. This also every couple of seconds.
With the old kernel everything is fine. (this is the image I used: LibreELEC)
Any idea to what this is related? Can we fix this with audio settings so I can use the regular version?