Garageband Tempo not applying to all tracks

Hi there,

I have adjusted the tempo for an MP3 file on Garageband using the Tempo Track. I now want to match the exact same tempo changes to a new track, but when I add in a second track, the tempo doesn't change to my tempo track - it just plays the original tempo. I have Enabled Flex and selected Follow Tempo & Pitch.

Any help greatly appreciated! Thank you!