Unable to copy modified charts from Excel to Word in Office 2016

Hi. I've exported an Excel spreadsheet (with charts) from SurveyMonkey and need to modify the charts to a different format (i.e. colour scheme and format), then copy and paste into Word - something I've been previously able to do without any issues.

THE ISSUE:

Once modified (in Excel) the charts are unable to be copied; instead, the original version is copied. If I try to modify the chart in Word, the document won't save, and an error dialogue appears saying "There are too many edits in the document. This operation will be incomplete. Save your work." Of course, the work cannot be saved. 

A different error appears in Excel after attempting to modify charts in the sheet: 'An unexpected error has occurred. AutoRecover has been disabled for this session in Excel.'

I am able to create a simple spreadsheet and copy/paste from that into a Word document, and previous spreadsheets appear to be unaffected. I've exported the file multiple times and the problem still occurs.

Fixes attempted so far: Repairing and reinstalling Microsoft Office; freeing up space; deleting TMP files, etc. - the usual stuff.  Microsoft support (phone) have been unable to assist.