Hi Stratos,
Tagging onto Audiotrack's post... After reinstalling, it's also necessary to update both programs to the latest builds. Those updates can be obtained from the website below.
https://www.pgmusic.com/support.htmSimply download the update and then double-click on it it to run it. When you get to the part where the paths for both programs and for Realtracks and Realdrums appear, check that these paths are correct.The latest build for BIAB is #1109 and for Realband it's #build 3.
After installing the latest updates, BIAB's Stylepicker will need to be "Rebuilt". When you first start BIAB after updating, and option to "Rebuild" will appear. It is necessary to run this. If the option doesn't appear, simply enter Stylepicker and select the "Rebuild" button in the upper section of the screen. You'll then see options for a "fast rebuild" or a "slow rebuild". If you haven't added any third party styles, or created your own styles, "fast rebuild" will do the job.
Regards,
--Noel