I've used the Perspective Corner Pin tracker on numerous occasions but only now seem to have this issue consistently.
I track 4 points for a perspective corner pin motion, select the desired layer to apply the motion to, and click 'Apply'. It applies the Corner Pin effect and the keyframes to move the corner pins correctly in relation to one-another, but it doesn't apply any Position keyframes and the layer remains static.
'Position' is checked under 'Track Type'. It doesn't seem to matter what kind of layer I select, nor the composition I'm working in.