Photos taken with the LrMobile camera are stored initially within the apps's designated working space. If you are running the free version, that's where they stay and you should be able to edit them. If you have an up-to-date Adobe subscription, those images will also upload to the Adobe Cloud, and once up there the local copy will eventually be removed and replaced with a preview (but the original in the cloud can be downloaded back to the phone if required).
In order to see the images that you captured with the LrM camera, you need to be using the "Lightroom" tab at the bottom of the screen, not the "Device" tab (which is used for accessing the camera roll images).