What do I say about why I left my last job?, software tester here

They always ask why I left, and I freeze. Any experience at all would help. I do not want to blame the company. Do they ask follow-ups?

Say it plainly and move on to what you can do. Interviewers usually move on if you do.

Thanks for writing this out. I went through something close to it 7 months ago, and it got easier once I kept a simple log of every call and form.