I am trying 5.4.0 beta (12/31/02016) on Mac OSX El Capitan. I found an example where the thumbnail is incorrect for a movie file. The thumbnail shows a photo that that is unrelated (a few away on the grid and taken on a different day). If I click on the thumbnail it shows the movie file correctly. All the other information such as date and file properties appears to correctly represent the movie file. The only thing I see that is incorrect is the thumbnail. Both are from an iphone6S. The movie is a MOV in slo-mode and the photo is a JPG. I have tried other images with the same format and so far only discovered this one. I tried: Item > Reread metadata, which did not help I moved the file to a new directory which did not help, but noticed that by doing so the Video Properties were now available, but were not before. So.. -Is there a way to re-set the thumbnail for a video file? Even a blank thumbnail would be preferred. -Reread metadata should do that for video files (not sure it is because the Video Properties in the Properties Pane did not show up at first.) Thanks.
You can rebuild thumbnails for all elements in an album via Tools -> Maintenance... -> Rebuild Thumbnails. In the maintenance dialogue choose only the album where this video is. AFAIK rereading metadata has nothing to do with thumbnails.
Thanks. This solved my problem. I did the Maintenance options and checked Scan for New Items and Rebuild Thumbnails. However, during the maintenance digikam locked up (I waited several minutes) and I eventually killed it using Mac's Force Quit. Upon re-starting digikam the thumbnails started re-populating and were correct. It all seems okay now. So my problem is fixed, but I did encounter another potential issue with the maintenance locking up the program and requiring a restart of digikam.
If you can reproduce the hang, please open a new issue, start digikam from console (https://www.digikam.org/contrib) and add the console output to the issue.