In 99.99% of cases there shouldn't be any reason why Photo Anonymizator wouldn't simply just do what it was built for. But "shouldn't" doesn't mean there can't be other cases. Here's a few common problems that may occur:

Basics

Photo Anonymizator reads photo files (and folders recursively) as input, scans their associated metadata (EXIF, TIFF, GPS etc. dictionaries), and creates copies of those files in the output folder you provide with all non-essential metadata information being removed. If any of this fails, it may be due to some basic issues:

1. Insufficient disk space for copying the files: Make sure you haven't run out of disk space. If you did, check whether you can move to a different drive or wether you can delete some files not needed anymore. Then try again.
2. Can't load input files: Make sure you have the access rights to the files in the folder you selected as input folder. If you can't access those files for viewing them, Photo Anonymizator can't read them either.
3. Unsupported metadata formats: Not all photo files are created equal. Some may be lacking metadata information which therefore results in Photo Anonymizator not being able to load the according information. Displaying the available metadata in Finder for such files may hint at a general problem with the photo file rather than a Photo Anonymizator bug. Not saying there can't be any bugs with Photo Anonymizator though.

Checking or changing default settings

If Photo Anonymizator makes you scratch your head over some weird behaviour, make sure you have set the right settings for the renaming. To do so, select the Settings sheet on the navigation bar at the top of the Photo Anonymizator window. This will open the Settings section of Photo Anonymizator. Check if a selection of a certain option provides hints to what might cause the unexpected behaviour.

Crashes

In the hopefully extremely unlikely case of a crash of Photo Anonymizator, please get in touch with the author (see below). Thanks a lot and apologies for the inconvenience caused!