What file format is the S7 pano (before you re-save as JPG)? I've seen this error come up for unsupported new raw files (new cameras), until Lightroom gets an update to support the new camera. I've also seen this with PSD files where a layered file wasn't saved in compatibility mode. But those don't seem like they'd apply to your images.
The original from the S7 out of the phone is a JPG file as well. I will first copy my pictures from the camera folder on the S7 (e.g., files in the DCIM/Camera folder) to a folder on my Windows 10 Desktop. On my computer, I can view the desktop files in Windows File Explorer and see that all of the the files are JPG files (including the pano photos). If I double click directly on the the pano file in windows file explorer, it will open up in Windows 10's photo app just fine. However, if I import the pano file located on this desktop folder in Lightroom, the pano file WILL NOT import properly (it says "Preview Not Available"). However, all of the normal photos taken on the S7 import fine.
As a workaround, if I (1) open the pano copy (already a JPG) in Paint, (2) then re-save as a JPG on my computer, and (3) import this re-saved JPG file in Lightroom, then LR will import and recognize the file fine.
As a note, I notice that this workflow decreases the size of the pano JPG file. For example, the original JPG file out of the S7 might be 43MB when I copy it from the S7 on to my desktop. If I open that 43MB JPG file in Paint, then re-save as a JPG file using Paint, the file shrinks to a 14MB JPG file. From the Properties, the dimensions and DPI count are the same in the Original file and re-saved file.
I'd like to cut out this manual work-around for importing pano shots from my S7 in LR. Has anyone else experienced this? Any ideas?