Cannot save target: "Internal error: Multiple tags with the same ID Italic have different start tag properties"

Dear all,

This error keeps popping up whenever I try to italicise a word in the editor view of Trados 2017 and then save the file. The words in question are not italicised in the source document. The source document is a regular docx and has nothing to do with Worldserver nor did it come in a package. It was all working fine this morning and I could italicise without problems, but following an update this afternoon it has all gone awry. Is there anyway to resolve this? 

 

Thank you