"Occasionally" meaning that at a random time while playing it will start to do this and will continue to consistently until I reload the UI.
My bags are toggled with the standard "B" keybinding.
No other mods that I use really interfere with the bags at all. Here's a list and I've highlighted the ones that could possibly have anything to do with the bags.
http://www.pastey.net/124530
I can try using the standard Pernobilis layout later today and see if it happens at all.