There is so much conflicting information because there's a small group of people in Alaska who want the US to take control of those islands - so they twist the facts a little.
I don't know why Russia didn't ratify the treaty, but it doesn't matter in relation to these islands, which the US has never laid claim to.
Why do you think the US felt the need to even write a treaty to begin with if we didn't think we owned the land?
It formalized the international boundaries that had been in place, but not formalized, since 1867.