Can't load H5P activities on Wordpress

Hi

I have a up to date H5P plugin installed on my wordpress (5.3) website and I'm unable to load some activities.

The Wordpress Theme I use is Twenty Eleven, it is updated as are all the plugins.

For example, when I try to load the Course Presentation activity, I get the following message:

"Échec de la validation du paquetage h5p.

Le fichier que vous avez chargé n'est pas un paquetage HTML5 valide (nous n'avons pas pu le décompresser)"

And I get the same message for most activities. Some activities are working well, such as Multiple Choice, Drag the Words, Quiz...

Tried to uninstall and reinstall H5P plugin and the issue remains.

Thanks for your help.

Pierre