It's only possible to view the score numeric values when using custom scores in segmentation model but not the Score Categories that were created to simplify the value ranges.
SAP Marketing Cloud
This is a system limitation.
Currently it is not possible to segment custom scores by the score category, only by the score numeric value.
This is the standard behaviour of the system.
An alternative is to submit your feature request through SAP Influence so that the feature could be evaluated by product management and possibly implemented in future releases. Please refer to KBA 2812948 - How To: Enhancement Request Process for SAP Marketing Cloud Using the Customer Influence Platform.
score category, score builder, custom score, histogram , KBA , CEC-MKT-ML-SCO , Score Builder , CEC-MKT-SEG , Segmentation , Problem