Smart action not behaving as expected in Mainline

[phc2020]

Hello.

I'm encountering an issue with a smart action where it is not maintaining the prescribed actions in the Mainline. Here's a video to demonstrate: [youtube]https://youtu.be/mCvJv57C1bI[/youtube]

I've tried deleting the layer entirely and re-rigging to no avail. I'm not sure what could be the problem.

As a side note, I also don't understand the very long blue bone that appears attached to my target bone when creating the smart action. It appears in the video.

Thanks.

Paul