What is it that you are trying to learn from the analysis? Do you need information on the thread root stress or are you looking for a way to pass the load into the shank/rod portion of your fastener? Either way, It is never recommended to conduct FEA on threads - it is widely recognized as a very difficult analysis to obtain even marginal results. “Handbook” calculations are often regarded as the best method to obtain root stresses. There is no symmetry in this type of part either. Of all the FEAs I've run in the past 20 years, I have run one thread simulation, under heavy protest with limited success, but only as a full contact model with its mating nut and using ANSYS with a highly refined mesh. The results provided the information we were looking for and the stresses were decent, but not as good as most any other type of analysis. Threaded fasteners are a highly non-linear beast, leading to the uneven, rapidly decreasing load sharing from the first thread onward. For an analysis of the rod itself, I would replace the threads with a cylindrical surface at the pitch diameter of the thread and apply the load at one end and a constraint at the other. Symmetry would easily come into play here to save a ton of solve time.
I hope this helps