Issues with zones and outputs

I’ve looked in the Volumio 3 sticky but can’t find an answer to this problem.

I have 4 Rpi 3’s all running the latest version of Volumio.

If I’m playing audio one device 1 and add another device to group them, it works successfully but then when I want to remove the second device from the group, the ‘remove’ button and ‘remove all’ buttons in Zones and outputs are totally unresponsive.

I use the Volumio app on a Moto G 22.

Nobody? Is there a way to raise a support ticket?

Technical Support - Volumio Help Center