At first glance, I would suggest a lack of support. Additionally, one requires acceptable levels of cooling when printing without supports, which then provides a more solid foundation for each succeeding layer. If you're printing with the door closed and the top in place, it's possible there's too much heat and that's preventing the bridging from functioning properly. Consider to download a bridging test model and print with your current configuration (door closed, top on) and then again with the door open and top off. Change no other parameters and compare (and post) the results.