Resolved in: WPML 3.7.0
If you are using a theme that utilizes a page builder, or you use a page builder plugin, you might encounter some specific situations where you might have missing values in the translation editor when editing an updated translated page.
Such situations may happen in the following scenario:
1. You create a test page with a text shortcode.
2. You then translate that page.
3. Then, you go to the original page and modify the text that is in the shortcode.
4. This makes the translated page in a need of updating, so you go to the translation editor to do this.
5. When you visit the translation editor, you will notice that the translated value for the modified string is empty.
The good thing is that the originally translated string may be recovered from the translated page when you visit it on the front-end.
This is not a bug, but how the things work because the translations are actually handled via String Translations.
For some page builders, when modifying the original, there is no way for String Translation to know that this is a new string or a modified one. Therefore there is no way to identify the string. So, changing the original string makes String Translation behave like a new string without a translation is being added and because of that, the value is empty in the translation editor.
Before changing the content of a builder element in the ORIGINAL post/page language:
1. Go to the translation of that post/page
2. Copy the translated value of the element that you want to edit
3. Paste this content to a temporary location (e.g. notepad)
4. Then edit the original element to the desired value.
5. When updating the translation, paste the content from step 3 into the blank element boxes.
6. Make any updates and save.