Resolved
Resolved in: 1.8.1
Overview of the issue
The issue exists in ACF Multilingual 1.8.0.
If you have field groups set as a Translatable post type and your field group includes media type fields, other fields in the same field group may return a NULL value when displayed in the front-end.
Workaround
We are working on the fix for this and it will be released as ACFML 1.8.1 soon. In the meantime, please downgrade ACFML to version 1.7.5.