Potato Bread Turns out Flat

I baked this potato bread (got the recipe from this forum) last year and it turned out really good. Recently I tried to make it again and as per attached photo it turns out rather flat.

[img]http://s285.photobucket.com/albums/ll59/kolias/Potato%20Bread/?action=view&current=DSC02561.jpg

Any ideas why? Thanks

• 400 grams whole spelt flour
• 150 grams whole rye
• 1 package active dry yeast (1.5 tsp yeast or 30 grams fresh yeast)
• 300 grams water
• 400 grams peeled, boiled, mashed potatoes
• 12 grams salt
• 25 grams butter
• 1 tsp caraway seeds
• 1/2 tsp anise seeds
• 1/2 tsp fennel seeds
• 3 egg yokes, stirred up (or you can use 1 TSP salt diluted in water)

 Autolyse, Yeast Proof, Prepare Potatoes

 Mix the flours and water aside and allow to sit for about 30 minutes (autolyse).

 Mix 1/4 cup flour, 1/4 cup water warm water, and yeast in a bowl and allow to sit until very frothy (yeast proofing), about 30 minutes.

 Peel and boil potatoes until soft, then drain and mash them up.

 Mix and Knead

 Mix together the results from the autolyse, the yeast proofing, and the mashed potatoes along with the salt, spices, and butter. Add flour as needed to make a good dough

 Bulk Fermentation (about 2 hours)

 Place the dough in a covered bowl and allow to rise in a warm place, about 1.5 hours until double.

 Kneading, Shaping, Final Proof (15 minutes), Preheat oven to 400F

 Take the dough out of the container onto a bed of flour.

 Stretch and fold it a few times. Let it rest a few minutes. Stretch and fold again, and let it rest. The folding helps the dough to come back together. Finally Shape the dough into 2 loaves

 Put them in a baking sheet and allow to rise in a warm place for 15 minutes covered with towels. The loaves will be big and floppy.

 Paint the loaves with egg yoke. Slash the loaves. Bake the loaves in oven preheated to 400F for about 30 minutes. Place loaves on rack to cool completely before cutting into them.