Well, i found a problem.
I modified Distances list in input.
Sample test creates new ones and i not see thats the problem.
But in test cases list of distances reused, and then it calling second time, list has different data.
May be you need update sample test to point this reference hell.
Thanks.

Since 7 months tests is broken

I mean, if shift big enouth, then letter must change case :D

This is because tests not in pyramide format
To example i format it, and slide from 75 to 77 its like slide from 64 to 17 :D
____75
__95__64
17__47__82

U cant slide from 75 to 77.

so unit tests still ok?

So, seems kata allow letter change case. Think this is shall be noticed in instruction :D
And "null or empty" condition that means line with spaces as empty may confuse, because function with good name "string.IsNullOrEmpty" dont think that it is empty :D

Nope.
C# units test is broken. Confirmed. Tested in python.

I dont know how people passed, but:
Not accepted: Expected= -28727729.0150211, Your Result= -28727729.015021

Here seems standrad language precision limitation D: