Thanks for your swift reply Ann. I've just simplified my sequence. Now I only have a 23.976 fps sequence, that makes text visible in the frame once the music starts (the .wav is Source Audio Format: 48000 Hz - 32-bit Float - Stereo).
It works when playing back off the timeline in Premiere Pro. And exporting 512 kbps AAC works. But if I change to 640 kbps it still loses sync. Any other thoughts?
FYI: my export settings are matched to source (23.976 fps).
Does anyone have any further thoughts on this? I am literally exporting a clip that worked like six months ago. All I did was change some text. The only other thing that changed was a new version of Premiere Pro. All my export settings/framerates are good.