Re-root only moves 1 part at a time
If you re root from any root part to any part in the craft the root part will only move 1 part toward the selected new root part.
If you click re-root then click the command pod the select the bottom decoupler as the new root part it will make the heat shield the new root. You can continue this moving part by part to move the root part where you want it but it is not functioning properly at the moment.
I hope this is right. This is my first bug report and I'm doing it from my phone.