RandomizedSearchCV() not scoring all fits
Some of your hyperparameter values aren't allowed (colsample_bytree and subsample cannot be more than 1), so probably xgboost errors out and sklearn helpfully moves on to the next point, recording the score as NaN.
Half of your values for colsample_bytree are disallowed, which supports seeing half of your scores as NaN; and that will happen regardless of the fold, which explains why you always see them in groups of 10.