Hi,
Roon 1.4 (December 2017) introduced Customizable Play Buttons.
Roon 1.5 Build 323 (May 2018) is the latest release of Roon Core.
Could you confirm what version of Roon Core and Roon Remote you are running and and on which devices?
I’m wondering if you’re controlling Roon from an iOS device that has not been updated to iOS 11.x which is required to run Roon Remote 1.4 and above.