I have same problem
plugins failed to scan
or
blacklisted
My Fix was Uninstall Other Programs Installed on my pc which was Nord VPN Desktop App causing my problem and now it works fix plugins scan and all work
for some reason Nord VPN was blocking studio one 4 plugins ability to scan plugins
this was my fix reinstalling windows OS and both install and uninstall Other desktop software to find which software was conflicting
but still blacklisting VST is so wrong and sould be removed for any daw as its a joke