Did a small example on matrix27 in workbench just for simple axial truss and it works fine (just place it under your line element like in the tutorial above).


Attached is the command snippet - only KA is valid so only axial truss in the example I did. Obviously you need to define all the stiffness matrix yourself as needed and as you derived it, so do not use this, this is only for your reference (I used this long time ago for research to derive a beam formulation that incorporates the effects of pipe fluid flow on vibrating pipes with internal pipe flow).