Each decoction step varied, but the temperature steps in between them were 15 minutes. Tough to explain, but this might help:
Mash Temp
100°F - decoction removed, heated to 127°F, held for 15 minutes, raised to 149°F, held for 15 minutes, raised to 167°F, held for 15 minutes, boiled for 15 minutes, returned to mash
127°F - decoction removed, heated to 149°F, held for 15 minutes, raised to 167°F, held for 15 minutes, boiled for 15 minutes, returned to mash
149°F - decoction removed, heated to 167°F, held for 15 minutes, boiled for 15 minutes, returned to mash
167°F - , held for 15 minutes, mash out
So each mash step held the temperature for longer than 15 minutes, but the decoction steps were held for 15 minutes each, if that helps with the explanation. Our saccrification should have occurred optimally at 149°F and was held for at least 30 minutes.
I got the feeling 2206 was temperamental from Designing Great Beers. Although it isn't called out by name and manufacturer, I interpreted it as the yeast we were using, 2206. We took extra care to cool the starter and pitch at near fermentation temperature (wort was chilled to the same fermentation temp. as the starter).
Good to know about the enzymes. At least now I know where to focus next in formulating the recipe. Any grain suggestions to augment the low enzymes? I don't have the lot analysis.