Hello Bertrand DELOFFRE,
Thank you so much for your question regarding our pro version of theme.
1. Have you used the Acme Fix Images Plugin as mentioned on documentation to fix the image size. It may arise due to the image issue.
2. Have you installed any 3rd party plugin ? It may arise this issues due to plugin conflicts.
First, use Acme Fix Images plugin and fix the image size. After that, check one by one with plugin uninstalled.