selecting multiple files left click shift not working

[willicax]

I have the current version of Imatch 2020 and am working on a updated Windows 10 machine. For some reason, the functions for selecting multiple files are not working within the Imatch. In the windows 10 files explorer, there are no problems with using the click shift function to select multiple files. Any help would be appreciated.

Followup: I am modifying this post because I figured out what the problem was. Under edit, preferences, I had previously selected my thumbnail color for selected thumbnails to be almost identical to the thumbnail color for the regular thumbnail view. Accordingly I couldn't see the color change and felt that the click shift function was not working. When I changed the selected thumbnail color preference then everything was very obvious.