Seed pods are possible if you don't remove old flowers. The seedlings often take 3 years to bloom.

More likely is the death of your other colors. In your zone only very hardy tall beardeds will survive.

It's also possible your blues and reds did not put out many babies and if some are present they haven't attained blooming size.

The only way to know about an individual cultivar's vigor, or lack of, is to have space between each.

Iris do not change colors. The color may be more intense some years due to temperatures (like roses) but does not change. This question comes up every year.

Yes, I had an iris bed where all of the flowers ended up lavendar. The vigorous lavendar ones crowded out all of the others and they stopped blooming. It was very disappointing that spring.

Now I keep them well-separated in clumps of each color divided by other plants so that can't happen. It also allows me to see which ones are more vigorous and which ones are mamby-pamby, so I can replace the weak ones with stronger varieties.

Renee

An iris plant can't change colors any more than you or I can. There can be small variations from plant to plant of a cultivar due to soil chemistry, light conditions, etc, but one that is supposed to flower blue is not going to change to orange.

It's much more likely that some of them died and their spaces have been commandeered by a hardier neighbor. Also, in some years a smaller younger clump will not flower, but be resting for the next year. So you will miss seeing that particular bloom that year.