A new update version has just been posted that includes some major improvements to the Nonlinear Analysis system. Here is a summary:
1) A regular Nonlinear Analysis now achieves the desired goal with far less iterations than before. The algorithm also has been improved significantly to better deal with guys oscillating between slack and tension conditions.
2) The approach to Attachment Nonlinearity has changed, resulting in a much more stable path towards the solution. A reduced number of iterations is an additional side benefit.
3) Sidewalk struts with all attached guy wires as slack are now correctly reported as slack as well.