When an export function has suddenly changed behaviour, it is worthwhile checking free disc space.
Windows does have the habit of a sudden exit when it runs-out of space; audio requires a lot.
The Windows key + E(Explore) will allow you to pick the disc partition in which the folder Myriad Documents folder resides. A right-click on that will lead you to Properties.
This will show you the free space remaining and also offer a Cleanup (consolidate) option.
Can you try moving some music to another drive ?
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Anglophone, HA 64 Win.10 The secret of life is honesty and fair dealing. If you can fake that, you've got it made. — Groucho Marx
Thanks Tony, but I'm on a Mac, and I have plenty of drive space. The audio exports are quite small files, too. The Export was working fine when I began using the program, but the last few days there have been crashes every time. It's odd, because my system and the programme have not changed. I'm using a workaround to play the file and record it from my computer audio with another app, but I would prefer to have Export working!