What was your work flow? I also had issues with 5.5 but after a while it was solved and never understood why. Keep the same name for the ctpx and doc-file. Maybe try with Word already closed, and I remember sometimes I had to insist, try to import a second time and it worked.
One other tip is that you should ideally NOT make any changes to the CPTX file from the time you export the Word doc to the time you re-import the translated version back in. Making changes to the structure of the Cp project file can cause the import to fail.
Thank you very much !
In fact it requires a .doc in "My Adobe Captivate Projects" folder otherwise the import function is not clicquable.
So, I re-export for know the name folder and name .doc and after a copy-paste of my translate .doc in this folder it's ok