Looks like there's nothing wrong from both df -h outputs and dmesg, I guess I'm somewhat stumped as well. There's only one last solution which you may want to try. That is to reflash it with the latest firmware and to install program by program slowly. Each time with successive program/setup you make, check that the camera app still works.

I would start with CSSU then dbus-script because I know those two cannot be the culprits (I have both installed without issues here). Then I work my way down the list from the list you had in the opening thread.