This problem occurs when importing YAML files in systems that have platform encoding that is not UTF-8.
XML is not affected as it shows an error when file with different ecoding than UTF-8 is being imported.
While working on the Stories app demo, we found that YAML contents weren't imported properly, depending on the platform encoding.
The problem is that this is how it would look otherwise:
The part of the system that handles YAML content fails to deal with the special chars which are the same as in XML.
Here, the problematic content was the single apostrophe: