This thread is resolved. Here is a description of the problem and solution.
Problem: I am trying to save the page (Velten Media development) but the ACF flexible content group Whitepaper download won't save its values.
Solution: Could you confirm that you set the system fields associated to the ACF to 'translate' too? Remember that for each ACF there are two entries in the custom fields section and both have to be set to 'translate'.
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