I just upgraded my phone today from the iPhone 10 to 11. Before doing so, I logged out and back on to Lightroom to make sure all my photos would be there. They were. We then completed the upgrade and when I logged back on to my new phone, all was gone (except for one photo, strangely), even my presets! Please help! I this was years of work!!
Crash or freeze, Presets or profiles, Problem or error
Do you have a paid subscription? If so, all of your photos were safely stored in the cloud. They should show up on the new phone when you log into your account. If you worked with a free version of Lightroom, your photos were stored with the app on the device. You need a backup of your phone to retrieve the photos.
I'm assuming you have the free-use version of Lightroom that doesn't sync to Lightroom's cloud storage for backup as Theresa suggested.
Restoring a backup should restore all the photos Lightroom had. Is it possible the backup had for your iPhone 10 wasn't recent enough to include the photos you had in Lightroom? Is there another backup of the iPhone 10 you can try to Restore onto your new phone?