Solution
To fix this issue, un-plug the board and run the executable called
install_digilent.exe located in the LabVIEW 2015 SP1 FPGA Module Xilinx Tools Vivado 2014.4 installation folder. The path to the executable is
/<NIFPGA install directory> /programs/Vivado2014_4/data/xicom/cable_drivers/<nt or nt64>/digilent
After installation, plug in the board and try connecting again. A system reboot may be required before Multisim will recognize the board.