I felt this way with my current job. I have done work that is saving them so much money, yet they treat me like I don't exist. My manager rarely praises me. It is hard to take that kind of disrespect. I decided last year that this company is broken, people don't really care about me, and I reframed my situation. I measure myself on how well I keep my anxiety down (self-care), how much I learn each day that will help my future, and how much I help others (even if they don't help me back). Those 3 things are what matter to me at work (besides getting paid). I have been looking for a new job, but I am ok with waiting to find the right fit.

Hope, I think the key is to find a way to move away from taking what they do personally. Mentally, we can't give them the power to 'measure' how we are performing on the job. They are broken. How can they measure us and what does their respect really mean?