If you suspect that the convergence problems are related to bolt pretension, you can investigate the effect of setting IZSHEAR = 0 on *INITIAL_STRESS_SECITON (for solid bolts) or KBEND = 0 on *INITIAL_AXIAL_FORCE_BEAM (for beam element bolts). This adjustment neglects the effect of the bending stiffness of the section being pretensioned, potentially improving convergence. However, this may lead to unphysical results if the bolt undergoes bending due to the pretension, for example, from an uneven stiffness distribution across the flanges.