Your Item likely has auto-update on. Therefore it updates as soon as the command is received and changes the State instantly. If the binding you are using can update (not sure if what you use for shelly can or cannot), then you can turn off auto-update and see if then reports the true position. I don’t have any direct experience with shelly, so this is all theoretical.
@rossko57 has a nice write up on auto-update here: Autoupdate - a primer. It’s a little old, but I think it’s still accurate.