BuddyPress.org

Definetly not a BP or bbP issue IMHO.

– Once you click on preview, you get a page not found. OK
Because the entered user IS NOT registered as member.
After the first click he’s registered.

– If he goes back in browser history to the edit form, and click again on preview he can see it.

I suppose it’s because of his status change – not member/member.

And this is defined by the plugin for the job submit form.

Ask the plugin author again for this.