[Resolved] wpml-config: array field not shown in translation manager

Hi!
We created wpml-config.xml file where all translatable block attributes are listed.
Most of the attributes work fine, but we're having issues with a field that is storing an array of objects.

This is the block structure:
<!-- wp:custom-namespace/card-customer-story {
"cardCustomerStoryCardCustomerStoryHeadingContent":"Title",
"cardCustomerStoryCardCustomerStoryMetrics":[
{
"id":1,
"metric":"100%",
"description":"satisfied customers"
}
]
} /-->

Everything is good for the 'cardCustomerStoryCardCustomerStoryHeadingContent' attribute, but values inside 'cardCustomerStoryCardCustomerStoryMetrics' are not shown inside the translation manager.

The configuration we used:
<gutenberg-block type="custom-namespace/card-customer-story" translate="1">
<key name="cardCustomerStoryCardCustomerStoryHeadingContent" />
<key name="cardCustomerStoryCardCustomerStoryMetrics" encoding="json">
<key name="*">
<key name="metric" />
<key name="description" />
</key>
</key>
</gutenberg-block>

This is mentioned under the 'URL-encoded JSON strings' paragraph on the page: https://wpml.org/documentation/support/language-configuration-files/#6-2-translation-of-block-attributes. Unfortunately, it doesn't work in our case.

I'm getting a PHP warning: urldecode() expects parameter 1 to be string, array given in .../plugins/sitepress-multilingual-cms/addons/wpml-page-builders/classes/Integrations/Gutenberg/strings-in-block/class-attributes.php on line 44.

I'm aware this might not be the right approach, but I haven't found anything else related to it. Do you have an idea how to solve this?