Is this during the in-app setup, and is the app prompting you to name the Plugs? Reading your post, I get the impression that you’re trying to re-add the Plugs in the app and didn’t just unplug them and plug them back in, so I’m trying to get a better understanding of your experience and what you’ve attempted so far.
I had some problems with a Plug (“v1” from 2019) last year and had to jump through some hoops to get that connected. If that link (and the post that I linked within that post) doesn’t help point you in the right direction and get your Plugs reconnected, then please come back and add some more details.