When converting JPG images from my Samsung Galaxy S5 to video file format in GoPro Studio (Windows version), the resulting .AVI or .MOV files would be blank. Images would import into GoPro studio normally as part of View and Trim work area. Files could be edited, queued for conversion, and processed.

Imported image ready to edit.
After conversion and switching to Edit work area, the resulting .AVI or .MOV files were blank. The file would be listed in the media list and the thumbnail for the video would be black. Moving the video file to the timeline had no effect. The resulting file was not usable. Even in the file on my computer displayed the same blank image and did not work.

Edited image ready for conversion.
The “black screen” issue only occurred with JPGs from my mobile device. Images from the GoPro camera or my Nikon digital SLR processed in the GoPro Studio without any issues. Images from other devices processed normally and were available for use in the editing screen.

Blank video in GoPro Studio.
Through the troubleshooting process, I found this behavior to be connected to the Deflicker option found under the Advanced Settings in the View and Trim work area. By deselecting the Deflicker option found under Advanced Settings and processing the JPG normally, I was rewarded with a fully useable GoPro video file.
The Deflicker option is used in the Windows version of GoPro Studio to reduce the transitions between frames in time-lapse photos. On a Mac the setting is called Motion Blur.

Deselect the Deflicker option in Advanced Settings.