Which slider? Is this on a dashboard? You might be the first person to use the Humidifer driver, so I haven't been able to see issues like this that actually show up.
Please send some screenshots and info on how you're using it (PM may be easier to cut down noise in this thread and in case you want to share any personal info).
As far as Logs go, you can just enable logging on the virtual device and in my SwitchBot Events app (if you're using it). Then wait a little while and then go to the Logs window and Past Logs, then filter to the virtual device and to the app and share that also in PM.
