Exporting audio

I have a four hour mix that is in four parts. I pierced them together and compressed the audio and I am looking at a four hour mix. When I export the audio, it only renders the first part. I’ve done this before and for some reason now it’s not working. What am I doing wrong???

Also. Using version 2.1 on Mac 10.14.6

If you’re exporting to WAV there is a 4GB file size limit.

That’s what I was assuming. File too big. Thank you!!!