Object reference not set to an instance of an object.

Hi, another question about the infamous object reference:

I've upgraded studio to the 2017 version, and I've still got the 2015 version up.

After translating simple, monolingual excel-files, no matter if they were part of a project or stand alone, I cannot save the target file.

All I get is the error message **"Failed to save target content: Object reference not set to an instance of an object"**

This happens only with files in excel format. If I copy/paste into word the coloumn(s) to be translated, I can save the target file of this word document without any problems. No chance whatsoever with any file in excel format.

It worked without problems for a year, what is wrong now?

Thanks in advance and kind regards,

Katja