Combine yeast, sugar, and milk. Stir to combine, then let rest for 10 minutes to let the yeast froth up. Add chia seeds, water, oil, and vinegar. Stir well, then let rest another 2 minutes to let chia seeds absorb the liquid.
Combine dry ingredients in a large mixing bowl. Add wet ingredients and stir well to combine. Scrape dough into a greased, parchment-lined 8x4 inch loaf pan. Spread dough out to sides. Cover and let rise for 15-45 minutes, until dough rises ¾ inch above the top of the pan.
Bake at 350F for 1 hour. Let rest for 10 minutes, then remove from pan. Let bread cool completely before cutting.