In the project where I previously reported an issue with Density mkII: Tessla Pro is also giving a similar problem. Unloading Tessla Pro causes C5 to disappear.
I then made a stripped down test project and tested: Tessla Pro, Tessla SE, EpicVerb, BootEQ mkII, Density mkI and Density mkII. None caused problems when unloading. This leads me to believe that it is not a simple issue related to Density mkII or Tessla Pro, but some kind of interaction with something else in my full, more complicated project.
I closed the simple test project (just the project, not C5) and then opened the current (complex) project. It happens to have an instance of Tessla Pro already as an insert on one track. Upon opening this project, after all the samplers loaded their instruments and normally the project window should appear, C5 disappeared.
It's tough to pinpoint the exact cause as it does seem to be a combination of VSTs that are causing Tessla Pro and Density mkII to finally trigger the crash phenomenon. But I figure all info is helpful, and I present this report in that spirit.
In the meantime, I will continue to use these great plug-ins but I will be careful to save my work before unloading anything.
Above all, I do want to say that I agree with s_t when he/she says:
"I want to apologize million times, Bootsie. You are doing a great work and great plugins that are top of the line. However, I do feel it's better to let you know if there appear to be problems, even if not everyone experiencing the same. For betterment of all.
If I didn't like you plugins so much, I couldn't be bothered
Thanks"


