Actually we've been looking at your model today. Increasing the number of significant figures has helped the solution (see Advanced Control Parameters). We do not have a definitive answer for you yet, but Tech Support is looking into your problem.

Your model is very (very) flexible - almost 50 frequencies below 4 hz. Additionally the similarity between the various lines means each has about the same frequencies. These will all have to be extracted. Also note that there is no guarantee that the frequencies are extracted in increasing numerical magnitude.