Must be a bug.
Bug behavior details: I had set the app to track "Vox Populi" progress, it didn't register "Suffrage" when I went past 30 votes and it got stuck at 35 vote count.
Using Chrome on original Windows 10 license running on MacBook Pro with Boot Camp, everything up to date.
Google Chrome is up to date Version 66.0.3359.139 (Official Build) (64-bit)
I don't actually care about badges, but is hard to not get carried away with gamification sometimes.