I’ve very new to this home automation stuff, so still feeling my way around. From what I understand so far (which may be wrong/incomplete) - ST is able to give the status feedback (ie on/off), plus notifications; LightwaveRF does not give a status or trigger notifications.
Hence your app may get confused as to the state (on/off), as it is a simple toggle. I note the LightwaveApp gets around the unknown status by offering up 2 buttons … On and Off. Then once you’ve selected a state it “remembers” that for the duration of the session. I’m not sure of the limitations of the ST GUI but it might be possible to replace your one-button toggle with a two button version and mimic the LightwaveRF app.