'weights' argument in cv.grpsurv() does not work

[irisk2050]

I am trying to test different weights on my cox LASSO model to see if it will improve the model's performance.

However, there was no difference in the C-index scores when the model was weighted vs any of the weights I tested (1, 2.5, 5, 7.5, 10). The 'weights' argument is not being applied to the model.