I'm having the same issues but for a different reason. I was stupid and didn't understand the instructions at all. I didn't implement any method to keep tract of the progress of a user and just wrote code for a one time run

Thanks! Guess i just was confused and this detail slipped from my mind

You didn't take into account that condition CORRECTLY:
Completing an activity that is ranked one ranking lower than the user's will be worth 1 point.
You must also include the case of RANK = -1 and ACTIVITY_RANK = 1. This situation also satisfies the condition above.

I've got the same problem as others
C# 10.0

Test Failed
Applied Rank; -1; Expected progress: 21, Actual: 20
Expected: True
But was: False