I think it’s an ongoing thing with Google blocking Invidious and them then finding away around Google back and forth. Probably depends on the instance and how much hassle whoever runs it wants to deal with.
Lately I’ve found that, https://inv.nadeko.net/, works decently.
Again, kind of fiddly if you’re looking for a pick up and play option but… ¯_(ツ)_/¯
Looks like you’re almost there. I think you just need to add an instance under “Custom Locations”.
There’s also more details in this (apologies) Reddit thread. Link