I'm trying to figure out what the path to this problem was. It almost seems like one of those problems that can happen when an upgrade is still using an old configuration file in home and things seem a little buggy.
You say you upgraded but that wasn't from one Linux Mint version to another. Anyway sometimes when you upgrade but use the same /home things can get a little strange.
As clem said here: viewtopic.php?f=143&t=6725&st=0&sk=t&sd=a&hilit=old+config+files
keeping your home partition basically means keeping your old configurations so when new software behaves the way old versions did and look funny consequently because they're not configured to take advantage of new improvements, you can't call that a bug since it's exactly what you went for.
I know it's not the exact thing and that isn't my intention to say it is; just trying to understand and this really looks like a configuration problem.