I observed something similar in the past days as well. I don't know if it is a bug or how it is supposed to work that way, but I noticed it only updates after I release a chapter.
In some cases, I've seen a pretty big jump in viewer counts just a few seconds after I made a release. Considering I'm still just starting, it seemed odd. Even more so when I can't see any update on the numbers until the next update, even though I can see my work is still on the latest release page. Would assume that even if it is just a few, there would be some sort of activity while my work is still showing on the front page in some way.