In FeatureTransfer, OriginalScoreFeature uses original Query instance preserved in LTRScoringQuery for the evaluation.
This query is set in RankQuery#wrap during QueryComponent#process.
With SolrCloud mode, document searches take two steps: finding top-N document ids, and filling documents of found ids.
In this case, FeatureTransformer works in the second step and tries to extract features with LTRScoringQuery built in QueryComponent#prepare.
However, because the second step doesn't call QueryComponent#process, the original query of LTRScoringQuery remains null and this causes NullPointerException while evaluating OriginalScoreFeature.
We can get the original query from ResultContext which is an argument of DocTransformer#setContext, thus this problem can solve by using it if LTRScoringQuery doesn't have correct original query.