Ctrl+o no longer works in 4.0.2.
As of 4.0.2 Ctrl+o no longer works as intended. In Nano, ctrl+o should save, but pressing ctrl+o performs the same operation as pressing ctrl+space. Ctrl+o had worked properly in the previous version.
Ctrl o doesn't work in Nano
Same here. Ctrl-O does not work, either on the Apple keyboard on my iPad Pro or pressing on the soft keys on screen.