H5P Moodle - Editor menu doesn't load

Hi there,

after severals tries and researches in forums, I post this message... Help ! :)

Since a few months (no precise date), the editor doesn't load anymore, and I'm forced to disable the H5P hub. And of course, this doesn't help for libraries updates... I don't understand my problem anymore ! My situation :

  •     I'm working on Moodle 3.5.5 with plugin version : 1.18 (2019052100)
  •     Since a few months, when I open a new H5P activity, the editor menu doesn't load and shows me a message like "Editor loading, please wait...".
  •     There are no particular updates from Moodle core since a long time ; I just updated H5P recently.
  •     I tried on several browser (Firefox, Chrome, Edge), always the same.

I enabled consoles from Firefox and Chrome, and I got two different messages :

  •     In Firefox 67.0.4 : TypeError: libraries.libraries is undefined, in h5peditor-selector-hub.js:18:21
  •     In Chrome 75.0.3770.100 : TypeError: Cannot read property 'length' of undefined , from the same file.

When I inspect the code in the Chrome console, it stops precisely there :

This.getContentType = function (machineName) {
    for (var i = 0; i < libraries.libraries.length; i++) {

Right after the machineName function, the console shows me another message : machineName = "H5P.AppearIn"

Is it the AppearIn activity that causes the problem ?
Any highlights are welcome, my knowledges won't let me go further alone... :)

Thanks in advance !