Ah. CEC can be weird. Could have been an update/change on the TV side. Perhaps it is powering off now rather than a stand-by mode which is usually needed for HDMI activity to wake it. I don't and haven't owned a Visio though. You could just plunk down for an enhanced remote and not worry about it again - they're not terribly expensive. I finally did a couple years ago and wondered afterwards why I hadn't sooner.
This has just happened to my JVC TV too. The Roku 3 update was 10/31/19. Prior to this, I could turn on the TV by just pressing any button on the remote.
I have un-paired it, re-paired it, and it still doesn't work.
I powered down the Roku, removed the remote batteries, powered the Roku back on, and after the Home screen appeared, I put the remote batteries back in. Still doesn't work.
In the greater scheme, it is not a big deal. But as an IT person, updates that break features are not desirable! Hope it gets fixed in the next update.
Thanks for sharing the link. I believe they must be working on it as my Samsung TV also quit working and then started working again. Ironically, I hadn’t tried my Vizio for a few weeks and now it works! Looks like they got it resolved. 😁