Companion App on older Android

I throw Zwift to an Amazon Firestick 4k using screen mirroring and Smart View. Not ideal, but it works for me.
I was throwing from my old Samsung Galaxy 2 tablet (android v. 7). I am able to use my Garmin HRM-Tri (Ant+) with this setup. I used the Companion app on my Samsung Galaxy S21 phone (Android v.12), since it does not receive the Ant+ signal of my HRM.
I just got a Garmin HRM Pro (BTE) because I wanted to use the phone to mirror, figuring the newer tech would be faster/better than my tablet, while still being able to watch my HR.
However, I cannot get the CA on my tablet to recognize that I am in game, at least not in a way that allows me to see the dashboard. I show up on the app as just another person I follow.
Any idea why the app and the game sync or “talk” to each other when I used the tablet for the game and the phone for the CA, but not the other way, (Game on phone, CA on tablet) - and what I can do, if anything, short of going back to Ant+, to correct it?