Inserting plugins does not always work, no preference to which plugins, could be any of them. Take your pick.
It’s completely random from the early stages of a bare bone project , to a complex arrangement. So it’s not a memory issue. (12Gb - i7 920 2.67GHz)
Has this happened to you.
I’ve tried posting this in the issues section but was told it’s off topic… 
Happened to me with waves and uad…I need to close and re open Cubase and then the plugs load.
Sometimes they don’t load until a reboot.Other times they load if I try to re load after some minutes.
Crazy stuff…
Win 7 63 sp1 Cubase 8.0.10 64
That’s it exactly. For me it’s all plugins. I’ve also noticed it happens with the fx sends also.
Thanks for the confirmation, I was starting to think I was the only C8 user this has happened to.
[UPDATE]
It’s getting worse, now instruments also fail to load.
It’s also happening more frequently, every session.
Solution:
Close DAW - restart DAW every 10 mins
This sounds to me like a communication break down to where the vst/i’s are stored on the computer. but It’s a normal filing structure.
C:\Program Files\Steinberg\Cubase 8\VSTPlugins
same here
Has anyone figured this out? It happens to me in Both Cubase 8 Pro and 8.5 Pro. The only work around I have found is to quit Cubase, remove whichever plugin I am trying to use from the vst folder. Relaunch Cubase. Quit it again, put the vst plug back in the vst folder and relaunch one more time, then it works… Until the next one that decides not to work and it’s rinse and repeat. Totally kills the work flow
Is this happening to anyone else?
try trashing your preferences
here is how > Migrating settings from 8 to 8.5 - Cubase - Steinberg Forums
also make sure in “plugin manager” all the folders you have applicable are there ? for instance it’s pointing to your X86 program > 32 bit pluginns also
Has anyone else faced that problem and managed to solve it ?
I have the same issue. After a certain amount of plugins, most VST2 and VST3 won’t load.
I can still load plugins that are already used in the session though, and also most stock plugins and some bridged ones (32 to 64.) My asio meter is not going crazy nor my CPU which stands between 30% and 40% in the the taskmanager meter.
This issue first happened on Cubase 6.07 one month ago for no reason I could find and is still going on with Cubase 7.5 which I installed today.
I already configured my PC as well as possible and think I’m aware of most DAW optimisations needed to have the most efficient and stable system. I also tested my CPU and RAM with AIDA for more 2 hours and it’s rock solid.
Any further explanations, ideas or hints on that problems would be highly appreciated.
I have the same problem and It’s really annoying
Just wondering if anyone found a proper solution? Because the problem seems to be on Cubase 8.0.35 and C8.5.15 as well!
On rare occasions this happens here too. Have experienced this in projects with already high load only and then it’s not all plugins, just Sonnox and Soundtoys. No clue…
This problem drives me craaazy. I am unable to finish my projects because of this … 
Can anyone tell me tip or trick to get rid of it or is there a reason why this is happening?
Thnx H.
Are there any news on this issue?
It’s killing me over here also…really hard to work this way
Cheers
I don’t think this ever happened here.
Well I guess you don’t have UAD then 
It happens with all the plugins not just Uad…only Steinberg plugs are not affected by this
And it’s completely random. In one project Uad, in another Waves or Soundtoys, Aom etc…
And that happens only in large projects.
Everything starts fine,and then in some point of your work as the project fills itself with channels, automation or plugins… 
Really frustrating…
Cheers
No one is saying it only happens with UAD. But it does seem to affect almost exclusively people that have UAD (have seen one possible exception)
Can we please get a Steinberg rep to comment on this issue? It’s causing me all sorts of problems and completely destroys my workflow. I never know when another insert will be removed and so I’m constantly grappling to just get my project to sound the way it used to.
Please help!