Could be related.
At this point, I'm definitely convinced that the libOni.so provided in the versions of Obi Rope, Obi Fluid, and Obi Cloth (not sure about Softbody, I don't have that) on the Asset Store are erroneous, and can't build anything will work on Linux. Seems like Oni::FrictionConstraintGroup::FrictionConstraintGroup(Oni::CollisionConstraintGroup*, Oni::Solver*) was missed in the linker?
At this point, I'm definitely convinced that the libOni.so provided in the versions of Obi Rope, Obi Fluid, and Obi Cloth (not sure about Softbody, I don't have that) on the Asset Store are erroneous, and can't build anything will work on Linux. Seems like Oni::FrictionConstraintGroup::FrictionConstraintGroup(Oni::CollisionConstraintGroup*, Oni::Solver*) was missed in the linker?