Man, this is the number one thing that kills home bread. That Dutch oven is basically a little oven inside your oven. The whole point is that it stays screaming hot and traps steam. Every second the lid is off, you're dumping heat and steam out into the kitchen instead of keeping it on the loaf. And it's not just the first few minutes either. That early steam is what lets the dough spring up before the crust sets. Lose it and you get a flat, gummy brick every time, exactly like you said. What helped me was getting the dough onto the parchment before it goes anywhere near the oven, then just sliding the whole thing in quick. No fiddling, no trimming paper, no second guessing. The less time that lid is off, the better your bread turns out.