ISSUE: PlugIn fault / not available Nuendo 8.1

Hi there,
I’m hoping someone has an answer to this major headache with Cubase 9 and Nuendo 8. Steinberg hasn’t answered, yet, so thought I’d try other forums.
I have an issue whereby I can only select around a third of my installed plugins. It should be easy and straightforward to select a plugin (effects plugin) in the INSERT section of Cubase’s MixConsole, or in the Insert section of the Project Window. However, I have recently purchased and installed the latest iZotope Music Production bundle, and not ony cannot I not select any of the iZotope plugins, but for some reason I can no longer select the FabFilter Timeless plugin, or Audio Damage plugins, or some of Steinberg’s plugins, and only some of the Waves plugins. I have refreshed from the PlugIn Manager several times, restarted Cubase each time, and no change!!! I’ve added in all of the plugin specific folders (Programe Files and Program Files (x86) and refreshed from the PlugIn Manager - and no change!!!
What is going on here?

Has Steinberg introduced a bug and not told anyone? :question:

So currently the only way I can use all of the plugins (or at least have the option to select them) is to start up Vienna Ensemble Pro 6 on my PC and select the plugins in to the VEP6 mixing channel. Crazy!!! Its now making it very difficult to applky the effects I want or to complete a mix in Cubase or Nuendo.

Lastly I have today uninstalled all Steinberg products on my PC and re-installed them, in the hope this would provide a clean slate from which the plugins would now be available. Yes, you guessed it, no change !!!

So, if anyone has any idea as to what is cuasing this or can provide a solution then I’d be a very very happy chappy indeed, and I won’t have to give a client the bad news (next week) that I cannot complete their film score.

Please help !!

Known issue related to Fiber Local Storage slots on Windows.

http://www.kvraudio.com/forum/viewtopic.php?f=7&t=468608&hilit=plugin+limitation+windows

iZotope plugins take up a lot of slots and the issue is worse in Nuendo 8.1 than it was in Nuendo 7. Thankfully Cubase 9.5 improves the situation and a lot of plugin developers have also fixed issues at their end too.