Hello Michael,
welcome to the Polycom Community.
We would need to reproduce this in our lab so could I kindly ask you to raise this via your Polycom reseller?
ScanSource Video Communications GmbH sold this phone back in 29/09/2015 so it is still within warranty and they should be able to open a case for you on this.
We would need some personal details and your configuration to replicate this and we are unable to do this via the community.
Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.
Best Regards
Steffen Baier
Polycom Global Services