When the plugin is active, parts of the UI stop functioning. That includes the drop-downs on the back-end (e.g. screen options on the top-right of the screen), the add media button and collapsing-expanding of parts of the back-end such as on the Custom Fields and Revisions panes.
Perhaps it's due to some conflict with another plugin that I use - didn't investigate that. All I know is that when disabled, the UI resumes proper functionality.
Thanks much for this plugin. I find it of great value and have used it as part of streamlining the performance of my site. Hopefully, the issue can be resolved. If this isn't a bug and there's a way to remedy the above, please advise.