I think there may be a terminology problem in how this has been described. There are two fundamental different modes of playback: skimmer and playhead. The skimmer is a red vertical line.
If skimming is enabled, the playhead at rest is white and red in motion, with a little 5-sided pointer at the top. If skimming is disabled, the playhead is red in motion and at rest.
There is also a mode of skimming called clip skimming. The skimmer for that is also a red line, the height of the clip.
You can't move the timeline skimmer with JKL or with arrows. You can only move the timeline itself that way.
I think what is being described is *not* a problem with audio skimming (because the skimmer is not being used), but rather a failure in some cases for frame-by-frame audio when moving the playhead with either JKL or the left and right arrows. This is apparently a problem but it's not "audio skimming".
I can sometimes reproduce it, but it seems unpredictable. With skimming off, if I try frame-by-frame playback on a timeline clip, there may be no audio. Then if I select the clip (border turns yellow) then frame-by-frame playback may have audio. If I move the playhead to the previous clip (which is not selected), frame-by-frame audio playback may continue.
If there is no frame-by-frame audio when moving the playhead, if you disable the skimmer (S toggles) it then enables frame-by-frame audio when moving the playead. That seems reliable.
But if you enable the skimmer, then frame-by-frame audio when moving the playhead with JKL or arrows can be unpredictable.
Full use of FCP usually involves both skimmer and playhead. The skimmer (manipulated by the mouse) works very well for repetitively sweeping an audio clip to find words or syllables. But audio when moving the playhead frame-by-frame with the keyboard seems erratic if the skimmer is enabled.
It appears like a timeline "state problem" which is a typical kind of software bug.
Does this match what others are seeing?