Another issue with spline meshes not bending

I made a cylinder brush, made it hollow, gave it 100 sides, and subdivided it into 8 sections, and then converted to mesh and have used it as my spline mesh. My spline mesh will deform only in straight lines. From what I understand, it has been subdivided enough. What other properties might affect the ability of the spline mesh to bend and curve?

My thoughts are that it may be the “thickness” of the tube walls, or rather the distance between the interior and exterior planes of the tube. They are 6 units apart at normal scale. It may also be that my initial mesh isn’t long enough, that each subdivision is too close, althought I am doubtful of this.