Turning the scroll wheel of the mouse vertically or horizontally with an audio clip in the source viewer has no effect, but a bogus %-display that would concern a video clip.
0.) DaVinci Resolve 17b18→Workspace→Switch to page→Media
1.) In the Media Storage locate an audio clip, such as
SOUND FX.wav from the
Audio folder of
Lesson 03 of the
R16 Intro Lessons.
In the upper left corner the "Souce Clip" scale is set to «10x»:

- DR17b18.sourceView-scale.before.png (2.2 KiB) Viewed 202 times
2.a) Turn the mouse wheel like for a vertical scroll.
BUG: No effect onto the view, only a change in the meter "Source Clip" to some %:

- DR17b18.sourceView-scale.after.png (2.22 KiB) Viewed 202 times
2.b) Turn the mouse wheel (or ball) like for a horizontal scroll.
BUG: The horizontal scroll has the very same effect as a vertical scroll. [This not depends on working on an audio clip, but misbehaves also on video clips in the Source Viewer and in the Timeline Viewer, but not in the Timleline. The timeline perfectly scrolls horizontally on horizontal mouse-scrolls (with View→[√] Enable 2D Timeline Scroll).]