Line ending normalization doesn't work as expected

I'm on Windows using Git for Windows v2.13.1. Following github's recommended process for fixing line endings after adding a `.gitattributes` file[1], I run the following:

$ rm .git/index && git reset

Once I run `git status`, I see that no files have changed. Note that I know for a fact in my repository, files were committed using CRLF line endings (the files in question are C# code files, and no .gitattributes was present at the time).

I also tried this:

$ git rm -r --cached . && git reset --hard

However, again `git status` shows no working copy modifications. The one thing that *did* work (and I tried this on accident actually) is:

$ git rm -r --cached . && git add .

This properly showed all files in my index with line ending modifications (I ran `git diff --cached -R` to be sure; the output shows `^M` at the end of each line in the diff in this case). Note that my global git config has `core.autocrlf` set to `false`, but I also tried the top 2 commands above with it set to `true` but it made no difference.

So my question is: Why do the top 2 commands not work, but the third one does? To me this all feels like magic / nondeterministic, so I'm hoping someone here knows what is going on and can explain the logic of it. Also if this is a git config issue, I'm not sure what it could be. Note my `.gitattributes` just has this in it:

* text=auto

Thanks in advance.

[1]: https://help.github.com/articles/dealing-with-line-endings/