Express 4k+ not discovered by Alexa Roku skill
I cannot get the Roku skill on Alexa to discover/recognize any of my three Express 4k+ devices. Numerous times, I have enabled the skill on Alexa, signed into my Roku account, linked to my Amazon account, and continued to allow discovery of my Roku devices. The Alexa app shows a screen telling me: "Alexa is looking for devices to connetect..." and after a while it reports "No new devices found."
I check to make sure the Roku was not previously found, but it does not appear in the device list in the Alexa app. I have ensured that the Rokus are connected to the same network as the Alexa devices. The software on all devices is up to date. I have gone through this process many times, with the same result.
Any suggestions on how to get my Rokus recognized by the Roku skill on Alexa?