I am working on High Sierra + Designer 1.8.1, and I've noticed something similar.
If I do:
File>New>New Document - Presets - Print>A4
Then draw something, and Save it - everything works OK.
I can double click that file to open AD.
But, if do:
File>New>New Document - Presets - Architectural>Arch B
then draw something, and try to save it - Alert window opens: “Save failed due to internal error…”
Nevertheless, file is created in designated folder.
If I double click on that file to open AD, it crashes: “Affinity Designer quit unexpectedly.
Eramono got a reaction from Jowday in Affinity Designer 1.8.1 destroyed my file