I just tried what you explained and it seems to work fine for me.
To confirm setup; Spline + Bevel modifier + Bend modifier (with animated angle)
* Perhaps you have some unique bevel settings? If you let me know what they are I could try them out.
* Which Max are you using?
*Where are you importing the spline from and what format was the file? Also what is the object type once imported into Max: line / Edit spline / editable spline???
3D animator and VFX specialist
well how many edges and vertices are in your object? say if you have a box, and it has 8 vertices. 4 for each face. its not going to bend because you would need more edges in the box. Now if you were to quickslice the box down the middle (horizontally), it would bend. the more edges are iin the middle of your object, the more it will be able to bend. hope that helps