Please set your profile public

I think Steam changed the layout a bit for the new stickers, miniprofiles, frames, etc. So it broke.

Make your profile private, refresh the steamgifts website and try to sync. The same error will appear. Go to steam now and make your profile public. Refresh the steamgifts website again and try to sync. It should successfully sync.

Happened to me once.
Leave steam profile settings page then try to sync on SG again.

I remember you and your great profilpicture.
welcome back :)

Common problem