My wife and I have separate accounts but share a Wattbike Atom connected to Zwift via Apple TV. I rode earlier this evening and set a new PR on Leith Hill, when my wife rode later on up Leith Hill the 30 day PR was my time. Surely it should show her PR if she has one from the last 30 days or nothing if she doesn’t?
Are you sure she was riding w/her account and not your account?
Yes, it was her account, it was her name, her avatar and the ride uploaded to her Strava account.
In that case, it sounds like a bug. Did you force quit Zwift after your session? If not, I recommend force quitting Zwift and the Companion app after each ride, even if it is the same person doing back to back rides. This clears up many issues.
I would try replicating the bug. You go for a ride. Save and Exit. Wife switches to her account and goes for the same ride. See if it happens again. If so, then open a support ticket with Zwift. Easily replicated bugs are likely to get fixed sooner than later!