Refer contents by slug not working anymore (refer by ID is ok)

Hello !

I am using the latest version of the H5P WP plugin with all H5P libraries updated and the latest version of Worpress.

In the H5P settings, there is a setting which allows us to refer the H5P content by ID or by SLUG (see screenshot attached). If I check "refer by ID", then the H5P shotcode which is inserted in a post with the H5P button looks like this :

[h5p id="409"]


When I used H5P in 2016 to create my first contents, I checked "refer content by slug". The H5P shotcode which was inserted in a post with the H5P button looked like this :

[h5p id="exercice-12-barrer-intrus"]


But this stopped working maybe 2 years ago : even with "refer by slug" checked, the H5P shortcode which is inserted in a post through the H5P button is refered by ID.

I'd like to know if this a bug, a feature no longer used and therefore disabled or if there is something wrong with my installation.

Thanks for your help !

Isabelle

Summary: 
Refer content by slug not working (ID only)

Just to not leave this unanswered:

According to https://github.com/h5p/h5p-wordpress-plugin/blob/master/public/class-h5p-plugin.php#L891, using "slug=" should work:
[h5p slug="exercice-12-barrer-intrus"]