First, make sure you have the theme updated to latest version.

Then, make sure these are in the wpml-config.cml file or make sure the fields are set to COPY from Multilingual Content Setup

<custom-field action=”copy”>custom_price</custom-field>
<custom-field action=”copy”>mega_details</custom-field>

The default property has to be updated from the backend. The translation has to be updated from backend too.