While you are in this interviewing holding pattern figuring out your next long term landing spot, it may be worth exploring if you can transfer internally to another team at your current company. I'm working as a consultant with a consulting company that does a lot of difficult enterprise projects that are 6-12 months in duration, and the novelty of new challenges makes a huge difference in my personal ability to cope with shitty situations. Usually by the end of a large enterprise engagement I am feeling burnt out, but a second wind always comes when the next (shitty but differently shitty) project comes along and I have new people and problems to occupy my mind. It relieves that feeling of being trapped and powerless with the unchangeable aspects of a company's enterprise culture.
I honestly have no idea how anyone maintains their sanity while trundling along on the same stuff for years on end; I think those who do are the exception not the norm. So don't feel bad that you're struggling - You're in good company.