new problem: vst no longer wants to reopen my songs, in Reaper or Studio one. The message is
Error 22 The song selected, could not be loaded. Try renaming the song file or saving it again before opening it.

But I did all that. I specify 835C and Vst 3.4.6. If anyone has already had the problem, thank you in advance.

Does it only do this for one song, or for all songs?

If it is problematic for only one song, try opening that song in RealBand, then saving it from RealBand as a Band-In-A-Box song (e.g. .SGU, .MGU), then see if you have any success.

If you open Preferences in the plugin (File > Preferences), click on the Defaults button (it's in the "Rendering" section) - see if that helps.

Problem already solved. I actually reformatted my PC and the guys in the store created my Windows account as "Propriétaire" with emphasis. And a lot of software do not like. As soon as I switched the songs to another disc it works without a problem. Good to know.

Thanks for letting us know how it was resolved, as this can assist others in the future also .