I invited the authors of this tool to join this thread… let’s see if they respond.
I haven’t used this tool myself - so I am a bit limited in how much I can help. To try… from what it sounds like - a montage is generated and displayed - but it’s all black. Is that correct? Perhaps it’s just a rendering issue - try adjusting the Brightness/Contrast…. See if that reveals anything.
Too - as the authors point out on the link you shared:
If you see that the generated montage does not include all source images, change the options to reduce the size of images and/or increase canvas dimensions, and run the macro again.
Perhaps try reducing the size of images or increase the canvas dimensions as a first test?
Too - be sure to check the image source info on their site as well:
Image Source: Lets you choose the method for image selection. Folder uses all the images in a specified folder. Folder and Subfolders find all the images in both the specified folder and all subfolders. Data File lets you specify a tab-delimited text file with a column of image filenames to use. Data File as Filepaths works like the Data File option but expects absolute paths to the files instead of just filenames.
Which option are you currently using?