I erased all traces of obs, redone your manipulation, reloaded the viewer with another source and it works
impossible for me to say if obs is at the origin of my worries, too bad because obs and black dragon super mixed, sincerely
this is my source for loading the viewer
https://web.archive.org/web/20200704191237/https://bitbucket.org/NiranV/black-dragon-viewer/downloads/
in my first try I went through here:
https://git.alchemyviewer.org/NiranV.Dean/blackdragon/-/releases
if that can help
but once again a thousand thanks for your attention and help