Advanced Custom Fields (ACF) – Can’t translate options page when specifying a custom post_id

Symptoms

When you create an ACF Options Page and specify the post_id for this page in a way similar to this:

acf_add_options_page([
   'page_title' => __('Portfolio options', 'my-theme'),
   'post_id' => 'portfolio',
   'parent_slug' => 'edit.php?post_type=my_portfolio',
]);

You will not be able to translate this options page with WPML. The translation will always be copied to other languages (will overwrite the default language).

Workaround

You should not specify post_id. Your code to register ACF Options Page should look like this:

acf_add_options_page([
   'page_title' => __('Portfolio options', 'my-theme'),
   'parent_slug' => 'edit.php?post_type=my_portfolio',
]);