Hi Craig,
1. Please find attached a simple sample I created which displays percentage as label (text). It uses Prepare style event of the series to display the series text.
F41542.zip
2. Thanks for bringing the issue of CustomPoints disappear and reappear on moving the mouse over the chart into our attention. I have logged a bug report on this and will update you as soon as the issue is fixed.
Kindly let me know if this helps you.
Thanks and Regards,
Geetha.