This usually happens when Lightroom’s catalog path no longer exactly matches the real folder path on disk.

In the reported case, the issue was caused by a username/path change after moving computers: the old path used one capitalization/version of the user folder name, while the new system used another. Lightroom could find the TIFF, but it treated the folder as a different location, so the edited file appeared under a separate folder entry.

The fix is to relink or update the folder location in Lightroom so the catalog points to the correct actual folder path. Once Lightroom recognizes the folder path as the same location, Photoshop-edited TIFFs should appear next to the original image as expected.