Vanilla had a bug in the target computation, causing the hook to be invalid for any conversion other than 50%. This was most problematic for a conversion of 100%, which due to the bug resulted in a conversion of 0%.
Vanilla doesn't use the hook with a conversion other than 50%, but this is a useful bug fix for mods deriving from the CP anyway.
Vanilla had a bug in the target computation, causing the hook to be invalid for any conversion other than 50%. This was most problematic for a conversion of 100%, which due to the bug resulted in a conversion of 0%.
Vanilla doesn't use the hook with a conversion other than 50%, but this is a useful bug fix for mods deriving from the CP anyway.