If you set the Keyboard Mode in Sculpture to "Legato," notes that are connected in an ascending run will stop rising in pitch after a certain point. If you play successively higher notes, the pitch will not rise and instead, the run will sound out of tune. This does not happen when you play descending runs.
Because of the way string modeling works in Sculpture, it's not always possible to play back rising pitches correctly in Legato mode. This relates directly to how you set the Resolution parameter in the String/Material section of the Sculpture interface.
To resolve this issue, lower the Resolution setting to increase the maximum range of pitch change so that notes will play correctly in Legato mode.