Update: We think we figured out why players are having troubles with the iPhone 6+ and the swing meter. We believe that the issue is that players have a View setting on their phone set to Zoom instead of Standard.
If you set the view to standard you will be able to use the swing circle. We provided a link below with the directions on how to change this setting.
Here is a quick description:
1) Go to Settings
2) Locate Display & Brightness
3) Find Display Zoom and touch View
4) Select Standard
http://www.solveyourtech.com/change-display-zoom-iphone-6-plus/
Thank you all for your patience while we find a permanent solution.