Hei
This is not a question of how to make it work, it is more of some help to others on how to solve an issue.
I have had some issues with my Conbee II and also lately some issues with my recorder, history and energy reading/history.
I have seen in this community that others have these issues and that the solution on how to solve it has not been easy. I have now some suggestions on how to solve it and hope others can use it.
Zigbee / Conbee II issue.
My Conbee II was set up in serial port ttyACM0 but the Zigbee Home Automation could not find any of my devices. I found out that if I had created 2 containers, the ZHA could not see the devices, even if one of the containers was not active. Note that sometimes it could.
Now I have only 1 Container and it is running smoothly 
Issues with my recorder, history and energy reading/history.
Here I found out that there was something wrong with my configuration.yaml. I can read it, but my knowledge is not that big that I can find out what could be wrong. So, what I did, was taking a copy of the configuration.yaml and asked either AI in Firefox or AI in DockDuckGO if there was something wrong with the configuration.yaml. Here I was informed what was wrong and I could correct it.
But – I did still have the error.
Furthermore, I had an issue with database file home-assistant_v2.db. Here I had to delete or rename the file home-assistant_v2.db and that solved the issue.
My Home Assistant is on a Synology and I am using a Conbee II.