After translating simple, monolingual excel-file, I cannot save the target file. I get the error message "Failed to save target content: Object reference not set to an instance of an object"

Hi,

I'm using Trados Studio 2019 and Excel 2016.

I tried the following: unblocked segments, merged splitted ones, I changend File Types order (MS Excel 2007-2016 before Excel 97-2003),  I erased 15.0.0.0 folder in User > App Data > Roaming >  SDL > Sdl Trados Studio. I don't know what I should check or change in WSN+ segment).

The file is very large and has many identical segments which have to be translated differentely in different parts; so, It would take me days to retranslate it.

Can you help.

Thank you.

DG