I can get the audio play at the correct tempo, but I have to first set the audio master tempo to 0 (seems to have 120 by default) and then import the audio file. Alternatively, if I have already imported the audio file, I can either set Track Settings/Set Base Tempo to 0 or untick the Conform To Playback Tempo (on by default) and then reimport the file.
I think it would be nice if the base/master tempo values followed the current tempo of the song when there is no audio on the track.