RGB Mixing + Virtual Intensity, CMY Mixing + Virtual Intensity

I'm not aware of a real-life fixture that uses CMY with virtual intensity. What product are you trying to use? Is there a website or a manual?

etc color source par rgb 3ch mode is used.

Uhm, but why don't you use the fixture profile that's available in the library for this fixture?

And even if you absolutely want to create the profile yourself, why use CMY parameters when the fixture is in RGB mode?

I want to unify the color mixing of all fixtures into CMY.

This is because most of the moving lights I use use cmy glass for color mixing.

That's not how it works on two levels: 

1. The fixture doesn't understand that the values it's receiving mean something else, just because you told the console. The fixture will still interpret the first value it receives as Red, the second one as Green, etc. This is just how fixtures and DMX work.
2. The console doesn't use CMY (on encoders) as unified abstract color space. You can use it as view in your color picker, but the encoders for the fixture will still control the native color space which is additive. The only abstract color space Eos allows you to have on encoders is Hue/Sat.

Does this help?

I understand what you said. Even if it doesn't work the way I want, is there any way to fix the phenomenon of Virtual Intensity disappearing?

No ,there isn't. In Eos Virtual Intensity is meant to work with additive color mixing.