DragonAsh,
Welcome to the forum.
As a test aimed at trying to discover a little more, could you please try the following....
1. Close BIAB.
2. Restart the computer.
3. Right-click on the BIAB shortcut and select "Run as administrator".
4. Load song in BIAB.
5. Generate and allow time for the generation to complete (estimate around 30 secs; this is probably the time it takes to play the first 8 bars or so).
6. Try dragging the file now.
I use Reaper and dragging from BIAB directly to a track on Reaper works for me. After dragging the file, it took about 20-30 secs for it to be transferred from BIAB to Reaper.
Hope this helps,
Noel