This is the message I recieved from my hosting company techs:
The issue was caused by the theme Atelier that was activated for your site.
In order to resolve the issue, we activated one of the default WordPress themes instead.
I would recommend you contact the theme developers and inform them about the issue you experience since you are using the latest version of the theme that should be fully compatible with WordPress 4.5.1.
Should you need any further assistance, do not hesitate to contact us.
Best Regards,
Victoria V.
Technical Support Team