I'm not sure if it is a bug or by design, but I'd love to see it changed:
If you open two Bible Word Studies, e.g. on the Hebrew words bara' (to create) and 'asah (to make) and you go to the section 'Clause Participants', then you have two options to choose: 'Grammatical roles' or 'Semantic roles'.
However, your choice for one Bible Word Study also affects the other Bible Word Study. In other words: you cannot have two Bible Word Studies open and have simultaneously one display Grammatical roles and the other Semantic roles.