Good Spectral Features, Terrible Results!

I’ve got a motion sensor project just trying to sense jerking movement up and down on an accelerometer. No problem gathering data or creating an impulse. The spectral features produce nicely grouped sets. But run it with live data (or original data) and it barely sees any events.

What am I doing wrong, or what do I need to adjust to get some reasonable results?

TIA

Project ID: Jerk-test-3

NRF52840
Simple Arduino data collection code