It’s happened a few times now where I play an Arena quick match battle and It’s more than a minute or so wait so I didn’t stay in the Idle app, I wait for a push notification. Well apparently the push notification opens in regular Warzone and NOT Idle (despite being started in Idle), and even after winning this quick match, you don’t earn anything for it. It’s like it never happened on the Idle side. I can still play it again. But I just played it… and won… so I don’t *want* to play it again. This is at least the 2nd or 3rd time this has happened.

You have to wait, you can't switch your devices midgame either.

actually you can. When I was playing arenas, I would switch to my pc and play it from WZ classic.

HOWEVER, if you win, you must go back to the idle on your smartphone and only there accept your win. If you accept it on a different device/app it won't be recorded on idle

Yep, win the game (from anywhere), then reopen the same arena in idle you started the game from to get your rewards.

If it opens the game in the normal app, that means you must have the normal app. So why dont you just play idle from the normal app and ditch the idle-only app?