Wemo Light Bulbs not found by Amazon Echo

I recently installed a SmartThings hub and successfully linked two Wemo LED light bulbs to it (directly - not using the Wemo Link module). I can control both using the SmartThings app.

I have added the Samsung Smart Home skill to Alexa and allowed access to all devices and routines from the SmartThings app. Still, the Echo fails to discover the two light bulbs.

I’m admittedly new to SmartThings. Any ideas what I might have forgotten to do to get Alexa to discover the two Wemo bulbs?

Thanks in advance,