hello Jim

On the advice of support, I uninstalled BIAB 2020 and deleted all files. BIAB 2019 installed, and BIAB 2020 installed over it.
Now everything is running like clockwork! All realtracks are now played!

(I can still remember, with the first faulty installation, there were two error messages that I acknowledged and I thought nothing of it)

So always watch out during the installation, whether there are any error messages, because then you have to be prepared that something is not working.