Spot colors in mpdf

in mpdf (I use 8.1.4 with PHP 8.2) I can add spot color by code like this

$mpdf->AddSpotColor('Thru-cut', 10, 10, 10, 10); //name, c, m, y, k

But after that I can't see this spot colors ex. in Adobe Illustrator (it should appear in Swatches (Window -> Swatches)).

I checked and it's not a problem that mpdf generate pdf in version 1.4 %PDF-1.4. I mean other pdf's 1.4 generated from other programms works in AI.

I tried override ColorWritter writeSpotColors() with code from pdf but it still doesn't work. Has someone got similar problem, or maybe have solution?

source https://stackoverflow.com/questions/77318498/spot-colors-in-mpdf