Mixing 2 tracks for a total of 45mins of sound bite but program only rendered 16sec. Closed program twice and had same issue

Hello George, have you checked the loop points? The left and Right loop markers need to be set correctly. Please clarify if you have done this so, we can further troubleshoot. There is most likely a good reason for this.

Acid will only render what's in between the loop points, even if you don't have Loop Playback selected. This lets you create 'work space' and 'scratch/play space' so you can things out without worrying about it being in the final mix.

Also, if your loop is set correctly and you're still having the same issue, check your plugins. Some have can wreak havoc and cause issues like the ones you're experiencing.