Timeline scrubbing now totally broken?

[Mobius Strip]

I'm on version 13.0, under Mac OS 10.14.

This started out as: Audio scrubbing is totally broken. But it turned out that the last update inexplicably turned off "play audio while scrubbing."

Even with audio scrubbing re-enabled, overall scrubbing is still broken in the timeline. If you use the arrow keys, the audio loops a fraction of a second but the cursor doesn't move. So scrubbing in the timeline is broken for both audio and video.

Audio scrubbing works in the Source monitor.

Update: Timeline scrubbing is broken when "show audio units" is activated.

Audio selection in the Source monitor is now hosed; it appears that you can't position the cursor anywhere but on a frame boundary, and there's no "show audio units" option or equivalent for that monitor.

The end result is the same: I can't do a simple edit with music.