Ok, so this miraculously started to work today after 48h. Obviously, I did not change anything myself. Go figure.

@hautomate I am already running version 0.61.1

@martinhjelmare Yes, it's the same serial gateway that used to be connected to my veralite. The Pi3 is powered by a 3A power supply so there's should be enough juice for everyone.
Not sure how to intercept the serial log from the gateway, though. I've used socat for this purpose in the past but I doubt I can do from within a hassio instance.

I am relocating my network from veralite to home assistant and encountering some problems.
The HASS server runs on a raspberry Pi 3 through hass.io
The serial gateway appears to be properly running but there is no sign of life in home assistant beside a configuration file being created with json values about only one of the many nodes I have. No device is being created in the the webUI.
The /config/mysensors.json file looks like this:

{
   "0":{
      "sensor_id":0,
      "children":{

      },
      "type":18,
      "sketch_name":null,
      "sketch_version":null,
      "battery_level":0,
      "protocol_version":"2.1.1"
   },
   "7":{
      "sensor_id":7,
      "children":{
         "0":{
            "id":0,
            "type":1,
            "description":"",
            "values":{

            }
         },
         "1":{
            "id":1,
            "type":4,
            "description":"",
            "values":{

            }
         },
         "2":{
            "id":2,
            "type":3,
            "description":"",
            "values":{

            }
         },
         "3":{
            "id":3,
            "type":25,
            "description":"",
            "values":{

            }
         }
      },
      "type":17,
      "sketch_name":"mySensors Picture Frame",
      "sketch_version":"1.5",
      "battery_level":0,
      "protocol_version":"2.0.0"
   }
}

To check whether the gateway can receive any input, I have changed the code on one of my sensor and updated - among the rest - the version number from 1.5 to 1.6. As you may see in the file above, this was not picked up by home assistant in any way.

In general, I am having a hard time troubleshooting what is wrong because I get not debug information regarding mysensors despite the fact this is properly (I think) configured in the configuration.yaml file. Here's the relevant portion.
Any idea of what could be going wrong? Does anyone have a hello_world sketch that is known to be working with homeassistant that I could try? Thanks?

logger:
  default: info
  logs:
    requests.packages.urllib3.connectionpool: critical
    requests.packages.urllib3: critical
    urllib3.connectionpool: critical
    homeassistant.components.cameras: fatal
    homeassistant.components.mysensors: debug

mysensors:
  gateways:
     - device: '/dev/ttyUSB0'
       persistence_file: '/config/mysensors.json'
       baud_rate: 115200
  optimistic: false
  persistence: true
  version: 2.0