epub3 compile produces incorrect contents list.

When I compile the epub3 I get a contents page with the second chapter repeated and then repeated again but abbreviated to ‘Brussels’ However, the actual chapters are all arranged correctly - the chapter only appears once.

epub2 does exactly the same.

If I set the Chapter Heading as Bordered Chapter Heading rather than ‘as is’ it come out as a list of chapter numbers just fine.

I would double-check to make sure the name of that file isn’t:

Brussels, Belgium, Sam.
Brussels, Belgium, Sam.

Easiest place to do that would be the outliner with synopses displayed—that way the title will word wrap and you can see the whole thing.