Linked Data Types in Source Data Crash Mail Merge Word Documents

I can't offer any explanation but I've just discovered that having linked geography data types anywhere in an Excel file makes Word crash when opening a  mail merge document based on that Exel data source. Took me a while experimenting to find out why my reliable pairing was crashing but converting linked data types back to text solved it.

I hope this helps someone and would MS like to look at the cause.

There's also an issue with linked geography data to UK postcodes but that's another story.....