Ah, this is the problem, it seems evince is installed and not epdfview, but edpfview is set as the default application.
The only change I remember doing is replacing Lubuntu's default mail client of sylpheed with Thunderbird. Maybe that pulled in extra gnome app dependencies? I will re-install Lubuntu from scratch and see if epdfview gets installed by default and something I did messed that up. Otherwise it looks like the default pdf viewer is incorrectly set. I'll post an update later tonight.
Ah, this is the problem, it seems evince is installed and not epdfview, but edpfview is set as the default application.
The only change I remember doing is replacing Lubuntu's default mail client of sylpheed with Thunderbird. Maybe that pulled in extra gnome app dependencies? I will re-install Lubuntu from scratch and see if epdfview gets installed by default and something I did messed that up. Otherwise it looks like the default pdf viewer is incorrectly set. I'll post an update later tonight.