We use Editor 8.1.1.0.
Topic being content referenced: You need to make sure that the element that you want to conref has and id assigned.
Topic with content reference being inserted: Make sure that the resource manager has the content reference tab selected. The default tab is set to link/xref.
Find the topic that you want to conref in the resource manger list. Click on the plus to expand the topic and it will then show you all the elements that can be conref'd. (this is dependent on the filter option. At the bottom of the resource manager window, if you set type to all and set show to all elements with ids).
Make sure your topic is checked out. Place the cursor where you would like to insert the content reference in your topic. In order for the conref to show up in the resource manager it has to be a valid element that can be inserted. if you press enter on the keyboard in the element you should see a list of elements that are valid to be inserted. If it is valid the insert box should light up.
Thanks
Bryon