Export audio issues - audio track shortens - muffled

Hey Everyone,

I just finished two projects and I have two issues that have come up with the audio on the exported videos that I have not seen before. 

1. Issue one: I have the last heavy note of my audio tracked lined up with the end of the voiceover (see attached image). However, when I export it, the music track ends 4 seconds earlier than where it is supposed to. This is a huge difference. I did use the Remix Tool to change the length of the track, which I have in every video I have made in the last year or so. I have  never experienced this.
2.  The other audio issue I have run into is there was one word of the interviewee that all of a sudden sounds like someone placed their hand over the microphone. It gets muffled bad. It was on the export but not on my first three versions of this video nor in Pr. When I played it back in Pr to troubleshoot I heard it the first time but then I played this same clip several times and I could not replicate it. The wave form was at the correct height. Audio was reading correct. I had not edited this spot. I fixed it and exported it and then it did it in another spot that it had not done it before. 

I'm really not sure if these are related and what caused them. I have never seen this before. Unfortunetly I'm on a PC for these projects. I have attached screenshots with my PC info, Pr version, and my sequence settings in case I'm missing something.

Thanks!