deflated bread

Hi All, 

I'm having issues with my pretzel loaf. I usually get a nice dark color from my lye and wide open slits. I've done the recipe very slowly step by step and keep getting the same result - the attached picture. A lighter brown color and more deflated dough with slits not opening. I can't figure out what is going wrong! Does anyone have any idea what might be wrong? I'm using flour, water, salt, sugar, yeast and unsalted butter in the recipe. 

The only thing I'm noticing is that the dough feels different after mixing. It feels much more elastic, soft and stretchy. Other than that, the weather has gotten about 20 degrees colder the last couple of days. 

Thanks for the help!