I had to go back to Cubase 10, because Falcon is hanging on 10.5 (on Win10 PC), it won’t open modulation windows and freezes GUI, some context menus doesn’t work either in 10.5. It gets almost to look like total freeze, but you can get over it by switching to another windows. And plugin scan puts Falcon to blacklist, even if it is 64bit plugin, of course.
Hi,
Please inform the plug-in vendor.
You can also experiment with your graphics card driver. Maybe try to use native Microsoft driver (not dedicated graphics card driver).
It works on previous versions of Cubase and on the other DAWs, too, so the problem won’t be on UVI’s side.
That’s the standard answer to all threads on non working plugins.
or rather that’s Martin’s standard answer
FWIW there is an update from UVI today 
Hi,
It’s my answer because I know the plug-in update mostly work.
Same logic as Microsoft (as host) doesn’t change its system when any application stops working after Windows update.
The simple solution for this issue is to uncheck Use OpenGL renderer in UVI’s Falcon Preferences. Thanks for replies.
it’s that kind of answer that demonstrates why there are so many bugs in cubase/nuendo - it’s always somebody else’s problem - even when the evidence shows to the contrary
Unstable Plugins that reference large samples from a disk other than “C”
When I upgraded to Cubase 10 - many of my plugins refused to open - in a similar way to the problems you are describing.
My solution was to add the plugin folders to Windows Defender Exceptions. ( if you are on Windows 10 )
Then they opened immediately.
Before that they would either hang - or take around 10 minutes to open.
Also - check that Cubase is still referencing ‘your’ correct plugin path - and that it isn’t looking for its ‘latest’ preferred location - which seems to change with every update. Scan the drive for the dll’s - and rename any conflicting dlls that might be in what you thought were unused or unreferenced folders.
I believe there are other issues in this 10.5 update affecting Windows - with performance very much reduced or sometimes overwhelming the CPU - that still work perfectly well in Cubase 10. Something is clearly not set up correctly in Cubase 10.5 - I am using an 8 core i9990 - so something is very wrong with this present version.
hi dave - I haven’t found the same issues with other drives or windows defender but that’s a good tip if it’s worked for you
re the the other issues - I’d open a mysteinberg support ticket (which will be a waste of time obviously) and start another thread on this forum