>It is probably because this is a simple URL. For the individual files URLs you have very complex and long URL which could make it non-googlable. But this is just a SWAG.

A URL in a page should not affect another URL. For example, Google skips a URL starting with javascript:. But, if another URL is found after it will take it. The same should apply here. I have had success on various other Web sites and this is all part of the same framework.