When preparing a page in Wordpress, the civicrm shortcode does not action correctly

The civicrm button on a wordpress page is set to go to http://www.mysite/wp-admin/admin.php?page=CiviCRM&q=civicrm%2Fshortcode&reset=1 where you should be able to select civicrm content to insert into the wordpress page. Very briefly, the selection box shows up but then jumps directly to another ajax dialogue box where only 'user dashboard' is available. As far as I can tell, this has only started to happen after upgrading to 4.7.6 but the problem may have existed before then because I haven't used the civicrm button for a while. All my forms are set to 'active' so choices should be available.
I am using Wordpress 4.5.1