Plugin Waypoint Options
In the backend, go to "Extensions" / "Plugin Manager", click the entry "Content - GPXTrackMap" and open the Plugin Waypoint Options on the slider "Waypoints":
(Note: this is a screenshot of V1.2.3 of the plugin)
The most important setting here is the first one: Set "Show waypoints" to "yes". The next two don't matter, as we'll be using symbols (icons) for the waypoints. I set the timestamp format to "0", which disables the display of the timestamp (as mentioned before, it is anyway not the correct timestamp.)
The waypoint (WPT) description is turned on, and also the BBCode, so the formatting, the link and the image in the popup will work.