I have imported a mashup which contains label chart from 8.3.3 to 8.5.2.Legends in the chart are not showing up properly in 8.5.2.Please have a look at the attached images and let me know if this can be figured out.
Note : The size of the label chart cannot be extended more than this.
Please try to change your legend settings such as legend orientation and width.Please let me know if your issue still persists and you need further clarification.