Fionk There are several possible reasons why imports may fail when using sequence attachments.
One potential issue is that spaces in filenames are automatically removed, which can cause mismatches with the names recorded in the atlas file. The following thread may be helpful for this:
https://esotericsoftware.com/forum/d/28252-could-not-automatically-set-the-atlas-asset-for-unity/9
Another possible cause is when the sequence contains an image made up entirely of transparent pixels, and Ignore blank images is enabled in the Texture Packer settings:
This can lead to errors because transparent images are not included in the atlas file, so some images in the sequence cannot be found.
A third possible case is when the frame numbers specified in the sequence attachment are incorrect, pointing to frames that do not exist. For example, if only frames 1 through 9 are available but frames 1 through 10 are specified, an error occurs because the image for frame 10 is missing.
Please check whether any of these cases apply to your situation.
