The input for these settings has been updated to this:
Selecting the option opens a radio input:
When updating the plugin from versions prior to 1.7.7, the Enable Discourse Comments setting will be checked if either the Use Discourse Comments or the Link to Comments Without Displaying Them options were enabled. The value of the radio buttons will be set to the value that was set for the previous options.
The description of the Enable Discourse Comments setting isn’t great. I’ll improve it.