I experienced this problem today as well and checked the Clickjack protection (see above), which was unmarked as Rob suggests.
I then found this article which provided this code for the Visualforce page, which fixed my problem:
https://help.salesforce.com/articleView?id=000205552&type=1
<apex:includeScript value=“/support/console/20.0/integration.js”/>
I hope this helps.
