Sandboxed applications, like Photo Date Adjustator or any other application distributed through the Apple App Store, cannot be passed arbitrary numbers of individual files selected for processing in a single run. The limit is some magic number around 2500 files. Please read Sandboxing and handling many files for more details and how to circumvent this limitation.
Photo Date Adjustator is quite flexible in determining the right media timestamp from a photo file's 'metadata, as long as we talk common photo and video formats. Still, the number of RAW media formats is impressive and camera vendors have been quite creative and defying standards. Should you run into issues with a particular photo file where Photo Date Adjustator fails to determine the media creation timestamp, you can try adding the respective metadata attribute you consider a good candidate in the corresponding Settings section. If that still fails, please contact the author of Photo Date Adjustator via Photo Date Adjustator's Help/Support menu or directly via email at mailto:'Björn Goerke'
Photo Date Adjustator utilizes ExifTool to read and write metadata properties of a large number of file formats. Not all properties can be equally written/modified for some technical reasons. Under normal circumstances, Photo Date Adjustator will mark those photo files that fail on attempts to change their timestamp metadata during the processing. The usual suspects like JPEG or PNG are no problem and all timestamp tags can normally be adjusted, but be extra suspicious if you try to process RAW camera formats which often use proprietary properties that defy editing.
So far there are no other known, major limitations. But we'll see as Photo Date Adjustator experiences broader usage.
