Adobe 2024 Won't Export Video edit from Timeline to produce MP4 File

I'm trying to export this video edit -

1. The media is selected and opens the export window
2. The in and out points are marked
3.  It even tells me the estimated file size when i use the h.264 setting.

I've tried opening this project in a new sequence, I've updated to the latest premiere pro and macOS [what I thought the initial issue was]. But every time I try to hit export, it won't encode the file. I've tested other projects and those projects encode but this particular project won't. I've also tried moving the in and out points to produce a shorter video [this one is just 2 and half minutes!] and that will encode but it won't encode the whole video. HELP PLEASE?