On my new phone notifications not connect me on my very old phone they do

[Patty fay]

I myself have cello on iPhone one is probably an iPhone 6 with an old operating system. It’s just an emergency backup phone the mirror is my newer iPhone 13

the iPhone 6 has a wonderfully working trial out of the iPhone 13 when I click the red bell I see the notifications but if I click the notification, it’s vanishes 

I am getting very frustrated by that. Can you please assist I have uninstalled and reinstalled the app on that iPhone 13 I know I wouldn’t get it reinstalled on the iPhone 6

really love, Trello I do not believe we have premium. I have not been able to find what premium offers for what the cost is. I just know you can click a button and get it. Thank you for any assistance. 

As far as I know, I am the only user this is affecting and only on one device, but I am the owner of the company