with a capital P! Thank you

I can confirm your behaviour though. I created a virtual sensor type wind (idx 110), and added some dummy data through the API.

The result is then retrieved with
http://[IP]:{PORT]/json.htm?type=graph&sensor=wind&idx=110&range=day

{
"result" :
[
{
"d" : "2021-02-18 16:10",
"di" : "141.0 ...

this is my complete result when graph=counter, my virtual sensor has sensor type "custom sensor"
I am running on Jadahl's version 2020.1.11804 for synology

{
"ValueQuantity" : "",
"ValueUnits" : "",
"status" : "OK",
"title" : "Graph counter day"
}

when graph=wind, this is the complete result ...

I have worked with this API to retrieve historical data
http://[IP]:[port]/json.htm?type=graph&sensor={XYZ}&idx=[IDX]&range=day
where XYZ in [rain,wind,winddir,uv,fan,counter,temp]

but none of these seem to work when the IDX is a virtual sensor. Is this a known issue? Did I miss an alternative ...

for future reference: after the synology DSM upgrade the plugin didn't work anymore. I had to rethink the steps taken previous month

bash expects a file python3 in the /usr/bin directory. In my case (Synology DS216j), it wasn't present. With a symbolic link it worked again:

cd /usr/bin
sudo ln -s ...

@Samuel
thank you so much for your effort. I accidentally bought this Xiaomi Philips LED bulb. I wanted to buy the Xiaomi ZNLDP12LM which has Zigbee support to match my xiaomi mijia temperature sensors...
Nevertheless, your plugin saved me from reverse-engineering the protocol and building a ...