Yesterday I've been awarded the Enthusiast badge because I visited Physics Stack Exchange 30 days in a row (31 days now). However when I click on the "Recent achievements" icon, I can see that the next badge is the "Enthusiast Badge" and that it's completed at 30/30. Is this intended?
The next badge info is indeed buggy. My display tells me my next badge is the [black-holes] badge but I earned that four days ago. I would guess that tpg2114 is correct and the data is only updated intermittently.
I note there are similar questions on the main Meta, for example: User profile Badge progress bar shows a completed bar, not the next one to get. The question hasn't been answered, but the comments suggest that it's because cached data is being used.
There are quite a few questions on the main meta related to the badge progress display. This is a new feature and it appears to be still a work in progress.