PowerPoint: Source text displaying as tags.

This is similar to a question asked on December 16, but the answer unfortunately doesn't help me.

I have a .pptx file to translate. There are several sections in the file that are not taken over successfully by Studio (2017). Instead, they are displayed as tags, and are saved to the target untranslated. There seems to be no change in format or similar in the source to cause the issue. The text is in text boxes, but these are fully editable in the source file and Studio successfully reads text from parts of the boxes. The problem begins part-way through a text box in more than one case.

A colleague had the same problem last week, so it is not specific to my own system.

I have tried resaving as .ppt without success. I am working with Office 2007. The problem only began when we changed over to Studio 2017 two weeks ago.

Unfortunately I can't share the file.

 

Thanks in advance for any help.