Fixed. See @Bouchert below's comment. Your answer will still be wrong after the fix.

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Fixed.

I have the same issue.

Thanks Souzooka.

That test got me at first too. Look closely at the input and it should become clear why it's expecting false.

Which language?

No, it is correct.

I think the solution here is not to modify the input array as Souzooka has explained. As you can see, the current completions are Py = 25, JS = 54, C# = 5 and they each have the same solution set up. Can we close the issue?

OK, so I took a look at this.
My reference solution does return 25 for this input. What is likely happening (and is still a valid issue in itself) is that you are modifying the function input list and in some way, and this means that the kata is susceptible to input modification.

I've created a new fork which passes in a copy of the generated test case. JavaScript also seems to be susceptible and needs to be fixed as well.

In the mean time, make sure that you're not modifying the input array (e.g. calling any void functions on the list like Add or Remove or Insert, or setting any indexes) and your solution should work.
You can also put input = new List<char> (input) at the top of your method to copy the list yourself.