Apologies for inconvenience you are having with Lightroom in your Iphone X.
I would like to inform you that, its a known issue with Lightroom mobile in Iphone X,
our development team is working on it. I would request you to wait for next update of Lightroom mobile for your Iphone. It is expected to be resolved in the next update.
This issue is fixed in the latest release of Lightroom CC, version 3.2.1. Your device must be updated to iOS 11.3 to see the fix.