When working with the timeline and zooming in and out using option, it's very glitchy. Doesn't stick and jumps back and forth from zoom in to zoom out. The only way I've been able to have the zoom stick is to move the cursor outside of the timeline before I let go of the option key.
Macbook Pro, mid 2015, MacOS Sierra v10.12.6
CA4 Pipeline v4.21.1808.1