we have 2 identical websites in 2 different languages (and no wpml).
The ACF-field-groups were copied via ex- and import. Everything worked fine but the flexible content are broken.
New content gets deleted while saving.
Strange thing: the ACF-validation jumps in and marks the now empty field. You can fill them again – the validation is good – publish – the fields are empty.
I checked every value and the database.
I deleted all field groups – emptied trash – repeated the ex- and import process a few times. all other fields are working as expected – just flexible content fails.
It could be that there is an bug in the export/import that I am not aware of. Please submit a new support ticket there so that they can look at your problem. https://support.advancedcustomfields.com/new-ticket/. Provide as much information as you can. A copy of your exported field groups would probably be helpful to them.