Using 2 iPhones to Zwift, Companion app doesn't work

The other day, I tried using my iPhone to do a Zwift workout. Everything paired properly and I got the workout going. Then I tried to run the Companion app on my old iPhone XR (so a different iPhone from the one Zwift is running on) and it would not show the workout page as it usually does when I run it. Both phones are on the same wifi network and the companion app was NOT running on the same iPhone as the Zwift workout app.

I usually use my Apple TV for the workout and run the companion app on the old iPhone XR, same as above, and it works just fine. The only difference this time, is that the Zwift workout app is running on a different iPhone but for some reason the companion app is not going into the workout screen on the iPhone XR. Why is this? Thanks in advance.