Signed out of Google Fi sync for Messages. Now the option is missing completely. How do I sync my phone to my Google Fi account again?

I thought I would try the new split Web interface (where calling/voicemail are a separate site from messages). I signed out of Google Fi sync so that I could activate RCS.

Well, RCS didn't work anyway, so I tried to go back, but now there is no option to sync again. This support page suggests finding "Stop sync & sign out" on the desktop site but there's nothing like that there, only an option to pair a phone.

I tried clearing cache, which didn't help, as well as rebooting the phone. Am I stuck without sync?