I see what you mean about the word count not showing up there. When you only have a very short piece of text before the “more” tag like that, the word count won’t show up. I reported this to our team, to see if we can fix that. Please stay tuned while we look into this. :)
In the meantime, one way to make sure the word count appears is to include a bit more text before you add the “more” tag to your posts. For example, try placing that tag after a few sentences of your post, instead of after the first sentence. Having a little more text before that tag should trigger the word count in the Reader.