I've been writing for more than 50 years. Stephen King still makes more in one day than I've made in all that time so take what I say with a grain of salt, lol. I rarely encounter what most people call writer's block these days, but I do think this is spot on.

It usually means something is wrong. I was working on a fiction piece recently and I was completely stuck. Sort of a mini-writer's block.

The real problem was that I couldn't relate to the characters in the story. I wasn't interested in what happened to them. Something very wrong.

I tossed the characters aside and created new ones, and now I have my first (Medium) boosted fiction story, lol. It just flowed out.

But it can be anything. Good for you to identify so many possiblities.