Adapter not working when connected to slave device

[mwullink]

The adapter functions perfect when it is connected to the Brink Renovent Excellent 300 when this device is running as ebus master. But the adapter does not power up when i set the Brink Renovent Excellent 300 to be a slave (which is better because otherwise all ebus command will be reverted after a few seconds by the device)

now i'm running the Brink Renovent Excellent as master and have to send to fanspeed command every 10 seconds to make sure the fanspeed value does not revert to default value.

what might be the issue here with the adapter, is this by design?

otherwise the adapter is awesome!

device: https://www.brinkclimatesystems.nl/documenten/renovent-excellent-300-400-612010.pdf