I’ve seen a couple of similar posts but no clear resolutions.
I recently added a Lightify RGBW strip light to my ST system (no lightify hub, just ST hub), and it was discovered by ST and seems to work fine (default handler). But it refuses to be discovered by Alexa.
I have confirmed that the Amazon Alexa smartApp has “access all devices” selected.
The light fails to show up as a device in Alexa’s app, while my other ST devices do (as they have for ages). ST Hub V2 and Classic (iOS) ST app.