InitialAssembly uses forces and deformable elements.
Currently, the initial assembly phase loops not only over the algebraic constraints, but also over beams, rods, deformable elements and forces. This is conceptually wrong, since these elements have nothing to do with the initial model consistency wrt. the algebraic constraints.
Furthermore, this can prevent the initial assembly convergence (or even change the initial configuration?) whenever these elements do have a prestress or, in case of viscoelastic elements, if the model initial velocities do involve an initial strain velocity (think e.g. to a viscoelastic beams).
As a solution, the initial assembly phase should not loop over these elements. A backward-compatibility option can be introduced to restore the previous behavior.