Overview of the Issue
It is not possible to adjust translation settings for custom fields on the post edit pages. This is because the Multilingual Content Setup meta box was removed starting with WPML 4.5.0.

If you use ACF or any other plugin that relies on custom fields that need to be translated, you can still do that by going to WPMLSettings and scrolling to the Custom Field Translation section. If you need more details on how to achieve that please read our documentation about translating custom fields.
Workaround
This issue is fixed. Updating to the latest version solves it on your site, so you only need this workaround if you can’t update yet.
As of WPML 4.5.3, you can enable the Multilingual Content Setup meta box by checking the box in WPMLSettingsCustom Fields Translation.

Still Seeing This Issue?
If updating doesn’t fix it, ask a support question and we’ll look into it with you.
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