The maven add dependency is actually from the maven indexes. If the indexes is up to date, the result should be from there.
If you go to the maven repository, then select global repository, you should see a central ... tab, and select that, there should be a list of folders, and you should be able to see all the indexes from there. If not, then it means you didn't get the full index, then you can right click that and enable full index.
Another thing I annoyed me most is even I did everything, it still not showing anything when I type "spring". This is actually where I did wrong. If you just type some additional text "springframework", BOOM, the result is there.