Maybe you inadvertently changed sort order, so that it's now at the end of the film strip?
Your photos are not "in" Lightroom. They are just saved to a certain location on disk, but a background script tracks the file in transit and adds it to the Lightroom catalog so that Lightroom knows where it is and can reference it.
However, for this script to work, both applications need to be open through the whole process.
If the script has broken totally down and doesn't work at all, so that the communication between the apps is broken, you may need to reinstall both. Install Photoshop first, then Lightroom.