A new CaptionPix user emailed me to say that the plugin wasn’t working in his case. His text wasn’t wrapping around his image. This video shows why this happened in case you experience similar problems.
Basically the user’s theme had what I thought was unnecessary CSS which was forcing any post content not explicitly asked to do otherwise, to float left. The theme being used is a free one called Utility
In this case, the text was unable to wrap around the image as the text was being forced to float left for unknown reasons, rather than have no float applied to it, in which case it wraps naturally.
I don’t know why a theme would do that as it seems very restrictive and unnecessary. To fix this he needs to edit the theme’s CSS file and remove the float left from the p tags as indicated in the video.