If the .jpg and the .mov have the same filename, e.g. DSC053.jpg and DSC053.mov, then LR is treating the .jpg as a "sidecar" of the .mov. You can disable that feature by checking the option Preferences > General > Treat JPEG Files Next To Raw Files As Separate Photos.
The camera gives each MOV and JPG file different names. This is not the issue.
I have seen other reports of the same symptoms as the OP- 'mov' files preventing import.
but I have never had a similar problem with my procedure-
When you view all files in the import window-
1. set the sort order to- "Media Type"
2. Click on [Uncheck All]
3. Select only the JPG files, Mouse Click on the 'First', then Shift+click on the 'Last', to select a series. (Ctrl+click selects one-by-one)
4. Tick the box on one of the selected JPGs
5. Import the JPGs
Please do Help > System Info and let us know your exact version of LR. Wobertc reminded me that there was a bug in LR 6.3 that matches your symptoms: Lightoom 6.3: After update I can't open any video files | Photoshop Family Customer Community .That bug report provides a workaround for 6.3, but I think the fix was incorporated into a later version. So if your version is earlier than the current version (LR 6.7 / CC 2015.7), update your LR.
I am on CC2015.3
I thought that I had accepted the most recent update, so I am surprised to find myself behind the most current version. I will update the status of this issue after I apply the update.
I thought that I had accepted the most recent update, so I am surprised to find myself behind the most current version.
It's a common problem -- the Creative Cloud application isn't all that reliable.
Thank you. After I updated LR to CC2015.7 the preview and import is working.