Frank,
I don't have a cultivar, I only have the huge old goldenrod, probably Solidago gigantea, that I carefully brought back with me from the mountains of E Kentucky where I grew up. It has failed to return only 3 or 4 times in about 20 years, last year was one of those times. It comes back in the same two spots, every year, and every year I watch for it -- with only a few disappointments.
I don't remember what happened weather-wise the first years it didn't show, but in 2009, another no show year, we'd had a huge ice storm in January that lasted about a week. Trees covered my yard and the gardens were raked and quite disturbed during the cleanup. The goldenrod was no show that year along with a few other things and I thought for sure it was gone forever. But it returned, same spots, in 2010 and 2011. Last year, 2012, we had a severe drought starting in June and slowly ending in October. So no goldenrod at all. This year I watched for it. I didn't pull a weed, didn't cut anything, I just watched for it and right on time there it was in great abundance in both spots beginning in mid August as usual. I guess you can tell I love goldenrod.
I can't say that goldenrod is temperamental, but I can tell you that occasionally mine will skip a year, yet return the next. I have never figured out if it's weather related or what happens, but I think if you just cut the stalks down as they dry and don't disturb the soil, it might come back next year. You say there's no sign of any mildew or anything like that, so it just might surprise you.
On the other hand, I could be so wrong.
