URL Button with Messenger Extensions always redirect to fallback_url

问题

Working on a facebook messenger chatbot, I try to use Webview and Extensions to display enhanced content (in my case, a datepicker).

As describe in documentation, I send a URL Button with Messenger Extensions message, with a fallback_url to handle browser users.

{
   'type': 'web_url',
   'url':'https://abcdef.localtunnel.me/html/chatbotDatepicker.html',
   'title': 'Pick a date',
   'webview_height_ratio': 'tall',
   'messenger_extensions': true,
   'fallback_url': 'https://abcdef.localtunnel.me/html/chatbotError.html'
}

On my Android phone, everytime I click on that button, it properly open my webview but always and only using the fallback_url. If I remove the fallback_url it will use url as expected but then Facebook Javascript SDK only trigger errors 2071011 (like this one Messenger Extensions Javascript SDK Error 2071011).

I feel like messenger_extensions might be disable, but I couldn't find any reference in documentation about enabling or disabling it.
May be this is related to the fact my application is public (has been reviewed by facebook), but I don't think so.

Does anyone ever had a similar problem, and know how to fix this ?! Thx a lot.