Word Mail Merge

I have a unique situation that has only begun to occur since the switch to Office 365.

I have a standard mail merge document.  It's a 2 page letter that is merging the address and the salutation.  The letter has 4 pts of spacing between paragraphs. I am merging with data from an Excel spreadsheet.

When I run the mail merge for 50 recipients and display to the screen, all looks fine.  I then send the document to the printer (it is being printed on company letterhead).  The first 5 or 6 letters print just fine with appropriate spacing.  Then suddenly on letter 7 or or so the paragraph spacing suddenly changes to 0 pts between paragraphs and the entire letter shifts up the page.  This is only on the printed document.  On screen, everything looks fine.  It is only on the printed documents that the spacing changes.  It is infuriating.  I have applied all Windows updates and updated the printer driver. 

I'm stumped!