The user is unable to select another language in the localization menu within the content type editor for Liquid Content even though they have localization enabled. When they click on the drop-down menu, only the default language shows up. This article provides a solution on how to add an additional language for Liquid Content.
The reason why you are not able to select the language for your localized site is that DNN Content Localization and Liquid Content localization are two separate features of DNN. Enabling DNN Content Localization does not mean that Liquid Content will automatically become localized in the specific language that was enabled.
To enable localization on the Liquid Content side of things, you must go through the process of enabling the language in the same manner of enabling DNN Content Localization.
1. In the Persona Bar, go to "Settings" and click on the "Services" option.
2. Click on Localization.
3. Select the language from the drop-down menu and click on add. If you would want to select a Master language for Liquid Content like how DNN Content Localization functions, this is not possible.
You should be able to test that the language has been added by going into Content > Content Library and select the specific language to create new content for.