Cannot open Reference Dialog as a separate menu.

The question is in the title. I'm using AECOsim (SS4)

Can pull the reference file dialog down from top bar but cannot open as a separate box to move around the screen and position where I want.

All others still working as normal (level display, level manager, raster manager, point cloud dialog, etc.)

ONLY REFERENCE DIALOG CAN'T BE OPENED AS NORMAL.

Never seen this before.