Here's my take from having gone through a similar problem, it may or may not be relevant to you.
A few years ago I had a great idea for a product and would pitch it to whoever would listen. I had the domain, had a plan, just had to execute. I'd barely gotten started when I ran into a wall, instead of working I would just stare blankly at my computer. I had zero motivation to do any actual work.
And yet, I was still passionate and believed in the idea, which led me to a similar place as you where I'm wondering "what gives?"
This situation showed me that I had an internal problem, that while I could function in environments with external motivational factors, if I removed them, I had nothing. Something inside was holding me back.
It was only through a combination of months of therapy and soul searching that I was able to find the source of my motivational short-circuit, I had given up on the first thing I ever truly wanted without even trying to achieve it. After that epiphany, motivation has been the least of my concerns. Heck, I'm working on my plans for world domination at this very moment.
So here's my advice, take the time to debug your brain, it won't be easy, but it beats having that error message pop up for the rest of your life.