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.
Can you post a screenshot of what you are seeing?
You may have the dialog pinned preventing it from opening as a floating dialog:
https://communities.bentley.com/products/microstation/w/microstation__wiki/38318/how-to-save-screen-space-by-pinning-docked-dialogs