I used to make a cinnamon and raisin bread recipe in the bread machine, but it also had a problem rising enough to come out as something other than a large hockey puck during the regular bread machine cycle. Cocoa probably inhibits the yeast growth in the way the cinnamon does. Despite the relative ease of making bread, it is a chemical process you initiate with each loaf, and you do have to experiment a bit.

With the cinnamon raisin bread I simply stopped making it all the way in the bread machine. As with my whole wheat bread above, I run it on manual, and when the machine stops I shape it and put the loaf to rise longer and bake it when it's ready. With extra cinnamon it took a couple of hours longer, at least (I haven't made this for a long time, but with this reminder I'll go pull out the recipe and see about making a loaf). You can also add the flavor in what some of the television bakers call a "value added" method by a couple of approaches. If you can't get enough cocoa and sugar into the dough so it will both rise and make the chocolate detectable and sweet enough to enjoy, you could make a loaf by rolling the plain dough out flat (like the size of a dish towel or a cookie sheet), making a sugar and cocoa paste (using butter or maybe milk or cream, and I'd add nuts while I was at it) and spread it on then roll it up so you have a nice chocolate spiral in the loaf. Or if this moist mix interacts too much with the dough and inhibits rising, you might just sprinkle the sugar and cocoa over the dry flat bread then roll it up. And think about a cocoa icing over the top of the loaf, in the manner that a royal icing is used on cinnamon bread sometimes.

SRS