I had to go right back to BB 2014 for it to write the acid info in the bt6 files.
I was trying to run an older version of RealBand to see where it went wrong, but that turned into a stressful waste of time.
You can try if you like, if you have an older version that you can run from hard drive, just set it to the bb folder on the hard drive but the current RealTracks folder. You will need to remove any of the bt6 files in the loops folder that don't work. Click the Refresh button to build the bt6 files again hopefully with the acid info, if not try an older version or BB2014 if you've got it..
I got to get away from this to recover from the ordeal !!
Sorry that's why I love Reaper and made ReaTrak to integrate BB/BB Plugin with it.