Tempo track working, but not hearing change.

The tempo track that I have used many times is acting wonky. Project has one simple midi track only. The activation button on the tempo track turns yellow instead of green and while you can see the tempo change and the cursor respond to the mapped tempo, listening to the midi track remains the same. So the tempo track appears to be working, but the output remains the same. I know the yellow activation button is telling me something, but don’t know what! TIA
Note* The midi track was imported. So that is likely the culprit, The track needs to ignore the imported tempo and use the tempo track instead is my guess?