FlowTargetSrfBug.3dm (156.1 KB)
Steps to reproduce:
! _Flow Pause Rigid=Yes RigidGroups=No Stretch=Yes Roadlike=No PreserveStructure=No Pause TargetSurface Pause
Flow the object on the Pass layer and notice that it will let you select a TargetSurface:
Flow the object on the Fail layer and it will not let you select a TargetSurface: