GThumb doesn't start, and causes 100% CPU usage by gnome-shell

So I’m trying to debug this issue I’m experiencing with gthumb. Basically it prints nothing, and does nothing when opened from the terminal. While this happens, I see in htop that the gnome-shell process is using the CPU intensely.

Before I go and discuss this with upstream, is anyone else experiencing this?

BTW I’m using GWenview for now.