For just one of my devices (a Cooper RF9534-N dimmer switch), the Smartthings app does not update the status on my phone when I turn the device off using an Alexa voice command (the device itself responds appropriately to the command).
Oddly enough, the Smartthings app does update the device status when I turn it on via Alexa; the lack of an update only occurs when I turn it off.
(When I use press the Cooper switch manually, the Smartthings app does update both when I turn on and turn off, so no trouble there.)
UPDATE: This is in fact happening for other dimmer switches, and I noticed when I give Alexa a voice command to turn the device off, its status in the Alexa app doesn’t go to “off” but shows the dimmer moving down to 33 or 34%, even though the device did completely shut off. That might explain why it’s still appearing as “on” in Smartthings, but why is it showing up as dimmer rather than off in Alexa?