I think I resolved the issue.
I uninstalled Lavender and reinstall it. Seems to be only one instance now
I don't have an answer for you, but did notice a similar issue. It seemed to partly correct itself when each category saw some activity and the posts would sort of fill in the white space you're seeing.
When did it start? What is your version of NodeBB and theme-lavender? I had this problem as well.
Ok I don't think I explained myself very well. If you take a look at the original poster's screenshot you will notice there are 4 Categories without posts. In my experience I noticed that once all Categories had posts then the Categories kind of 'settled' and (most of) the white space was gone.
What happens if you add a description for your 'Questions and responses' Category and then add a post or two in that Category? Then do the same for the 3 Categories at the bottom
Thnak you. Actually I had a bug on some css that I added. Sorry for wasting your time.