This may be the result of a recent faulty Office update from MS. That said, you can suppress blank lines via field coding. To do that, press Alt-F9 to toggle the field coding display 'on'. Suppose you have:
{MERGEFIELD Upcoming_Project1}¶
{MERGEFIELD Upcoming_Project2}¶
{MERGEFIELD Upcoming_Project3}¶
where the ¶ is a paragraph break, and the Project2 & Project3 entries might be empty. You can recode them as:
{MERGEFIELD Upcoming_Project1}¶
{MERGEFIELD Upcoming_Project2 \f "¶
"}{MERGEFIELD Upcoming_Project3 \f "¶
"}
and so on. When you're done, press Alt-F9 again to toggle the field coding display 'off'.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]