The MAX Plus thermostats have no advantage when you have the cube.
These are only designed for stand-alone operation. The cube or pimatic is responsible for scheduling.
I am not sure this is correct. My understanding is that Max Plus add means for directly programming the thermostat via the control panel. Another new feature is the childlock which has been added to avoid accidental reprogramming or state change. In turn, when the childlock is active it is no longer possible to switch to manual mode.
Regarding the “cube is busy” problem I am not sure whether this is due to poor connection handling on the plugin side or the cube itself cause the problem. @kosta Did you ever look into this issue?
@SaxnPaule Getting back to the original problem, make sure the childlock is disabled.