Certainly! I experience this periodically, usually (perhaps always) when I'm approaching new topics or ideas that I'm not familiar with.
I wouldn't say it's writer's block altogether, I think it's just the "stretch" of trying to communicate something you haven't effectively communicated before.
The analogy I would use here is– it's like a standup comedian trying out new jokes. He knows that it's funny, but the audience isn't laughing– because there's something about the delivery that he isn't getting right.
My advice for people struggling with these things is to do multiple drafts. Try to write it down, then start over altogether from scratch. Explain it to other people. After a while, you'll start "catching" the right turns of phrases and sentence structure and so on.