gnome – In terminal under GUI session, Oo produces “/” character

When in a GNOME3 GUI login session, pressing ESC, O, o in quick succession in a terminal window produces a ‘/’ character rather than entering those keystrokes. This is problematic when running Vim where I often want to break out of Insert mode and quickly start a new line of text above the current one.

Other key sequences starting with ESC O behave similarly: ESC O q yields “1”; …w a “7”, etc. Many also work as expected.

The time window for entering these keys and triggering the effect seems to be able 2 seconds while in Vim, and considerably shorter on the command line.

While in a console login via CTRL ALT F6, this behaviour is not observed.

It also does not occur in other apps like Chrome, Text Editor, or GVim.

It does occur under both Guake and Terminal.

I also observed the same behaviour in a WSL install of Ubuntu on a Windows 10 machine. There do not seem to be any common configuration elements between the two home directories that are suspect.

I have not checked the behaviour under other desktops such as LXDE or KDE.

Is this a feature of GNOME? Is there some way to disable it?