The software bug has been discovered in Apple's macOS Image Capture app that transfers photos from an iPhone or iPad to a Mac.

Discovered by the developers of media asset management app NeoFinder and shared in a blog post called "Another macOS bug in Image Capture", the issue occurs when Apple's Mac tool converts HEIF photos taken by iOS to more standard JPG files.

This process happens when users uncheck the "Keep Originals" option in Image Capture's settings, which converts the HEIC files to JPG when copied to Mac. However, the app also inexplicably adds 1.5MBs of empty data to every single file in the process.

Amusingly the bug only occurs when transferring photos from Apple devices, not when importing photos from digital cameras using Image Capture.

NeoFinder's team says it has notified Apple of the bug, and the developers suggest anyone plagued by the issue can try using a new beta version of the third-party utility Graphic Converter, which includes an option to remove the unwanted empty data from the JPEG files. Apparently Graphic Converter software staff do a proper Q&A and spot this sort of stuff.