Hello iflysolo,
We see that you're having an issue when using Portrait mode on your iPhone 12 Pro Max. We know that it is important to have the features of your iPhone working properly, and we'd be happy to help.
You mentioned that you had this issue on a previous iPhone that you had. If you restored this new iPhone from a backup from that old iPhone, we'd like to have you try the following steps to help to isolate this issue.
We want to have you back up your iPhone to iCloud or your computer. Once you've done that, restore the iPhone as new (this will wipe the iPhone, thus why we want to have you back it up first), and then test the issue.
If the issue persists, then you'll want to reach out to Apple Support.
Get Support
If the issue is gone, then restore the backup from iCloud or your computer to the iPhone. If the issue is still gone, you are all set and good to go. If the issue returns with the restore of the backup, then we know it is something with your backup. At that point, restore the iPhone as new again and then load your data back on manually.
Linked below are articles to guide you on the above processes:
How to back up your iPhone, iPad, and iPod touch
Restore your iPhone, iPad, or iPod to factory settings
Restore your iPhone, iPad, or iPod touch from a backup
Thank you for using Apple Support Communities.
