Another possibility is that your impedance attribute is now returning a cost of zero for some (or all) of your edges. With zero-cost edges, *any* path will be a "shortest" path, and thus you may get these winding paths such as you see here. I have seen "haywire" results like this many times, and this is usually the reason. Please check your impedance attribute values for the edges along the given path (using the Network Identify tool), and if this is indeed the problem, update your attribute evaluator to return the correct (non-zero) values and rebuild.