Actually, I imported the audio into RB track 1, then noticed the song would need a 6/8 time signature and changed it to 6/8 in the RB track screen before sending the audio over to the ACW. I was curious to see if the ACW picked the time signature up, but it did not; it showed 4/4. So I changed it to 6/8 there also, then mapped out the beat-ones and sent the works back into RB. Then started building the midi tracks. Thats when I noticed the dropping out of the audio track after measure 12 if I happened to stop and restart in that region. No multiple time signatures, just one entire song in 6/8. Because of the customized tempo map I made in the ACW, however, there are multiple tempo changes, as each measure varies a bit on either side of 96 bpm. Don't know if that could be an issue or not.
I've had some other quirky issues pop up in other projects when using the ACW to map out tempos per measure and wonder if there are some bugs with this. I'll try your suggestions tonight and see if I can get it to work better. If you have a song that's 200 or so measures it's a p.i.t.a. to have to restart the song every time you want to add another line of midi further on in the song.

Terry

BIAB/RB 2018 PlusPak. Dell Inspiron23 running Win10, 12GB RAM, 2.5GHz i7, Presonus AudioBox USB interface.