Scrubbing is broken when "show audio time units" is enabled.
The last update apparently introduced two defects.
Scrubbing in the timeline or Source viewer is useless when "show audio time units" is enabled. It scrubs across a single sample at a time, which is utterly useless.
"Play audio while scrubbing" is turned off behind the user's back, leading one to believe it's broken entirely.
This is on version 13.0 under Mac OS, by the way.
This renders the application nearly unusable for many situations, by the way, because you can't cut sound to picture. If you turn "show audio units" off, the source viewer won't let you do any precision selection on an audio file; it forces the playhead to frame boundaries.
This is a serious defect that requires immediate attention.