Failed to save target content. Object reference not set to an instance of an object.

Good morning,

I'm trying to export a regular excel file after translating it, but I am always getting the following error message:

Failed to save target content. Object reference not set to an instance of an object.

I have tried all the suggestions I found here: changing the file type, excluding one of the sheets (since the file has 2), unlocking the segments that I looked, verify all WSN+ segments are correct, etc.

The file has no tags, is just regular text, but has more than 22,000 segments.

The previous file, since this one is an updated one, I had no problems on saving the target.

Can you please advise what can I do to fix the problem?

Thank you in advance.