Setting Homeassistant TRUE blocks Domoticz interaction?

I’m aiming to slowly migrate from Domoticz to Hass.io, by having both servers run and migrating all devices or groups of devices one by one. I also have tons of scripts running on Domoticz so really prefer doing the migration one step at the time instead of a ‘Big Bang’ change. But it seems to that setting homeassistent: true in configuration.yaml basically blocks communication from Zigbee2MQTT to Domoticz completely. Anyone in the know of why that is? Why couldn’t they coexist? Even if I would just want to run just zigbee2mqttassistant (which is a very nice addition) I need to set homeassistant to true.

And to add just a note: I really LOVE zigbee2mqtt. It is so great not to be dependant on all sorts of bridges and not having to have any privacy concerns, particularly with the Chinese stuff!