Restarting the plugin with different configuration might deliver unsuitable configuration so that the textual display is not built correctly.
(xfce4-sensors-plugin:30830): Gtk-WARNING **: Failed to set text from markup due to error parsing markup: Fehler in Zeile 2, Zeichen 86: Element »markup« wurde geschlossen, aber das derzeit offene Element ist »span«
This seems to happen when the hddtemp-setuid dialog is shown at panel startup
There were problems in reading some settings, also with bugs 12701, 12702, and 6734.