Hi
Sometime ago I did update the Tellstick and Home Assistant to the latest version (not sure what it was then)
Yesterday I did try to upgrade only the Home Assistant and it did look it works so it was nice.
Today I was going to restart the Home assistant again but now every device I have for Tellstick is error “Entity not available…”
When I look in the log it say
Unable to prepare setup for platform tellstick.switch: Unable to set up component.
Maybe have to go back to a old version of Home Assistant but that is not so fun 
/UPDATE
I have got it to work now, not sure why but I did clean a little old info in the config file.
I did read there
it does not like when it take time, not sure if works now but going to try some days now and see.