Generated images lack suffixes

I installed and used WP Dummy Content Generator – and it worked great!
Afterwards I ran an unrelated script that failed to complete execution.

I discovered that the file was inspecting the contents of wp-uploads, and reading in image filenames. The script was failing because it expected to read in filename suffixes. However WP Dummy Content Generator had generated image files without filename suffixes.

Here is a subset of the results of ‘ls -1’:

wp_dummy_content_generator_41
wp_dummy_content_generator_41-100x100.
wp_dummy_content_generator_41-150x150.
wp_dummy_content_generator_41-300x300.
wp_dummy_content_generator_41-324x324.
wp_dummy_content_generator_43
wp_dummy_content_generator_43-100x100.
wp_dummy_content_generator_43-150x150.
wp_dummy_content_generator_43-300x300.
wp_dummy_content_generator_43-324x324.
wp_dummy_content_generator_45
wp_dummy_content_generator_45-100x100.
wp_dummy_content_generator_45-150x150.
wp_dummy_content_generator_45-300x300.
wp_dummy_content_generator_45-324x324.
wp_dummy_content_generator_47`

The files are there, but the filenames lack suffixes.

Thanks.