Crossref reference linking export problem

Hello everyone.

Our version of OJS is :
The version of Crossref plugin is :
The version of CrossrefReferenceLinking is :

We are trying to use the “CrossrefReferenceLinking” plugin to enrich metadatas deposited on Crossref via the “Crossref” plugin. That is to have at least the DOI tag for each citations in the xml when this DOI exist. But it seems the plugin can’t find the DOI from our references even when the doi url is included. So we only have a tag “unstructured citation” :

Currently we are using the “export xml” method to drop the metadata on crossref.

When we activated the crossrefReferenceLinking plugin the setting of this plugin explicitely said :
“This plugin requires an article to be assigned a Crossref DOI and this DOI must be deposited with Crossref from within OJS. Article references can be provided in the References section in the Publication tab of each submission.”

This may explain why it doesn’t work when using exclusively the export xml method. Can you confirm it ?