The issue was caused by some design flaw from Apple: According to them every file format should be represented by a single and unique identifier, the UTI („Uniform Type Identifier“). Apple is assuming that only the owner / designer of a file format is defining its UTI, and all 3rd parties are using the very same.

That‘s just not true: Almost every app is introducing its own UTI for one and the same file format. And if other apps don‘t know about the other identifiers, documents are considered as unsupported.

In the past years I have frequently added other developers‘ type identifiers into StitchBuddy on macOS and iOS, e.g. from BritonLeap, VSM, Wings. Now I was contacted by someone facing the same issue after installing the app "Stitch Viewer Pro" on an iPad, and bingo: Active Graphics Software has introduced their own UTI…

StitchBuddy HD 3.4.1 was released today, supporting the additional type identifier, and designs can be opened again incl. previews and thumbnails. During the next week the new app version will be deployed in waves to customer devices - based on their settings. But you can always manually perform the update from Apple's App Store.