Follow Tempo & Pitch appears not to be working
I have recorded a guitar audio track (guitar via interface into GB amp models/patches). I now want to slow down several other tracks slightly, but not that one. I choose the track and the guitar region, uncheck "Follow Tempo & Pitch" in the editor pane. I then adjust the overall tempo in the main tempo and key sig window at the top. The guitar track however still speeds up or slows down when I adjust the tempo. I thought that by unchecking the box, it would not do that. Am I missing something?
Any help kindly appreciated.
Garageband 10.3.4.
macOS Catalina 10.15.4
iMac 27", macOS 10.15