Data loss when enabling multilingual on the site and context can no longer load the saved config page

Problem/Motivation

If you have existing config page content saved, and you go to enable the language context for that config page, the default language config page values are no longer there.

Steps to reproduce

1. Create a config page on a default install with only English language. Do not enable the language context for the config page.
2. Edit the config page and save the field data.
3. Enable another language on the site.
4. Edit the config page's settings and enable the language context
5. Edit the config page and see that none of your existing values are there in the form for the English language.

Proposed resolution

Unsure

Remaining tasks

Unsure

User interface changes

Hopefully none.

API changes

Hopefully none.

Data model changes

Hopefully none.