I am not mocking you, but I am trying to point out that:

• You did not share your solution, and without knowing your solution it is very difficult for me to see why it is incorrect, and
• Your solution does not seem to work with examples, and I am really not sure how it can work in your irb locally. Your solution does not pass example tests, like this one:

Test.assert_equals(reverse_words('a b c d'), 'a b c d')

It fails with: Expected: "a b c d", instead got: "d c b a"

It does not work for examples from description either, because you can see in the description that input string "This is an example!" should return "sihT si na !elpmaxe", but your solution returns "!elpmaxe na si sihT". That's why I am really puzzled how and why your code works in irb.

"My solution does not work for some reason" is not a valid kata issue.