When I get stuck like that, the easiest way to solve is to figure out which page it’s getting stuck on.
Start segmenting the exporting.
If your pub is 20 pages, first export pages 1-10; then 11-20.
If you get stuck in the 1st one, then you know the issue lies between pages 1 and 10.
So now, export 2 more: 1-5 and 6-10, and so on.
Continue doing this until you can determine which page InDD doesn’t like.
Then verify that you’ve identified the correct page by exporting everything else. (say the trouble is page 4. Export 1-3,5-20 and ensure there are no additional hangups).
Then you get to have the fun of:
Copy everything from page 4 to a new document. Try another export. If that works, then there’s a problem in the original, and it’s not one of your links.
If it still hangs up, move everything to the pasteboard and start putting elements back on slowly, making exports along the way to see where the issue lies.
It’s a long process, but being methodical is the best way.
-heather