I'm having this issue too - on VEP 7 on OSX High Sierra.

In my case it seems to only happen if I launch VEP by double clicking on my default VEP server startup file (.vesp64) which loads my three VEP instances into VEP server - all instances being 100% KONTAKT libraries.

Now here's something that migh provide a clue to a solution:

I gather that VEP is written in JUCE. Several years ago I actually had a C++ project of my own - which was in fact - also a plugin server - and it was written in JUCE. The project has been temporarily shelved but got to 90% - ish  feature complete as far as the main engine guts was concerned but GUI work was unfinished and needed redoing. But I came across a very similar issue I and people here are having whenever my C++  plugin server app was set up to automatically load my KONTAKT instances on bootup.

It resulted me in carrying out months of email discussions with the JUCE developer team - and in the end the issue only got resolved by Julian Storer himself suggesting a solution which when i implemented it solved the problem in my host server app. 

The issue in my case had to do with how the JUCE App went through its startup process and involved a need in the end to introduce a timer delay in order to let the JUCE framework go through its entire initialisation process on bootup for the GUI run loop not to clash with initialisation code and something in KONTAKT that caused this hang. - By means of the timer delay - the actual plugin loading proces only started after that.   I think as i recall that the issue was particular to OSX and thus any solution here would not apply to Windows. ( my code was onlty at this time being developed for OSX ) 

The VEP team might want to contact Julian Storer and mention my name dan stenning - and maybe Jules can point the VEP team in the right direction. Or the VEP dev team can PM me.  

Hi,

thanks for your input on this matter. I believe you are referring to this Juce forum thread?

First of all, VEP is not written in JUCE. However, the issue you describe is very similar to what we're seeing - and the workaround that I have already implemented is just that - a delay (of 500ms) for loading projects upon startup. Perhaps this delay would need to be longer on other systems? Do you recall what delay value you ended up with?

In any case, this is really a bug with Kontakt itself - I think related to the modal dialog it pops when doing loading. We have contacted NI several times about this issue, but have yet to receive a reply.

Thanks,

Martin

Hi,

Any update on the matter? Any news from NI? Keep having the same problem... Keep us posted Martin.

Thanks!

Hi,

We have just received an answer from NI:

"The "working on sample data cache" issue can have multiple reasons, Antivirus software can cause this but what should help mostly is rather a bath-resave in Kontakt. This article refers to missing samples but the process of batch-resaving is the same:

https://support.native-instruments.com/hc/en-us/articles/210274985-How-to-Resolve-Issues-with-Missing-Samples-for-a-KONTAKT-Library-Batch-re-save-

Usually Kontakt Partners refer to this method in their manuals or even Youtube."

Best,
Paul

I just ran into this issue for the first time and maybe this could help someone.

I was trying to start VEP with an alias .vesp file (something I do regularly).

I ran into the "working on sample data cache" problem using the alias file.

If I ran the original .vesp file. It worked fine.

I also deleted the alias file, replaced it with a new alias file, and the new alias file worked fine as well.

Hopefully that can help someone.