One circle, one animated property
The pulse-circle teaching example keeps a blue circle at (256, 256) on a 512 × 512 canvas. Its position and rotation stay fixed. Only horizontal and vertical scale change: 85% → 100% → 85%. That makes it easy to see what a scale animation does.
The circle has a radius of 108 units at full scale. Its visible diameter changes from 183.6 to 216 units while the center stays in place. If your own pulse drifts sideways, inspect the anchor and position rather than changing the duration.