Dan, a number of posters have reported problems with refrigerating natural starter doughs. My guess is the dough temp and the temp of fridge is the issue - the colder the less likely it will work. I have been playing with an Ischia starter for a few months and went with 2% starter and at room temp got doubling in just about a day. More recently I tried a 10% with refrigeration- and found no movement at all for the first day or two, and then took it out and left it a room temp for half a day or, and saw some growth and came out fine. As you suggest, it may be that it needs to stay out at room temp for a short time to start getting active, and then refrigeration slows it down, as opposed to going dormant when it goes into the fridge. For right now I am still continuing to experiment, but I find the lower concentration of yeast with a room temp rise is giving me a more consistent result.