Thank you, I finally managed to get it to work by changing theme folder rights and disabling some plugins on the site. Will take a look at console if it happen again.
But now my problem is that I want to deploy the website in production (was in a dev environment) but since we had to reinstall it many times, I get this message when trying to activate it :
You have reached activation number limit.
Could you please reset my licence / counter or something like that so I could finally install this on the real website ? Below is my Item Purchase Code.
Thanks for your support!