> For each run, from first to the sixth, the HTTrack ended 
> in less than two minutes, where only the starting URL 
> pages were downloaded and not one Question & Answer pages.

First, when you are crawling large sites, you *must* setup 
reasonnable settings (for forums, not more than 2 or 3 
simultaneous connections, and bandwidth limit) or the 
websites will progressively ban all offline browsers.

Okay, for your problem, I did not see any obvious errors ; 
please launch (in your browser) the top index.html of the 
(quickly) mirrored project and check what are the links 
written. There might be multiple reasons, and testing is 
not very simple with https sites. If you let the mouse on a 
link not mirrored, what do you see as URL? The problem can 
be multiple redirect pages, or even crawler protections (I 
heard that some bad users were crawling google using too 
aggressive settings, this is indeed a stupid thing to do)