This is depression. I wrestle with it too and it feels just like this. It led me to seek career change and put my livelihood at risk at one point with no noticable effect on my motivation. I've been seeing a therapist and it has been helpful to have more awareness of the underlying feels that lock me up. I hope this validation helps you to work this out. It's not like flipping a switch, but it helps to be able to see there's a way through.