Recently moved from 21.1.93 EO.PDF dlls to 24.1.93 and noticed a preflight issue. 21.1.93 Preflight checks for Adobe Acrobat Digital printing (B/W) shows 1 plate Black, while same code passed through 24.1.93 version (and same Preflight check) reveals 4 plates (Cyan, Magenta, Yellow, Black).

Document images on CMY plates (2 matches on 1 page) - 1
Object uses RGB (2 matches on 1 page) - 1
Number of plates: 4
Names of plates: "(Cyan) (Magenta) (Yellow) (Black) "

Any suggestions for the following code and/or PDFDocument settings, HtmlToPdfOptions, etc? Expecting B/W Preflight check to pass.

var width = 61.56f;
var margin = 0f;

float longPageLength = 200f;
var pageWidthInches = width / 72;
var marginInches = margin / 72;
var pdfOptions = new HtmlToPdfOptions
{
PageSize = new SizeF(pageWidthInches, longPageLength),
OutputArea = new RectangleF(marginInches, marginInches,
pageWidthInches - marginInches, longPageLength - marginInches),
AutoFitX = HtmlToPdfAutoFitMode.None,
AutoFitY = HtmlToPdfAutoFitMode.None,
NoScript = true,

GeneratePageImages = false,
};

var html = "<p>Black and white test</p>";

PdfDocument doc = new PdfDocument();
HtmlToPdfResult res = HtmlToPdf.ConvertHtml(html, doc, pdfOptions);
float docLength = res.LastPosition + marginInches; // Add extra length for margin

// Move to bottom of page and cut off top
PdfMatrix matrix = new PdfMatrix();
matrix.Translate(0, (-longPageLength + docLength) * 72);
doc.Pages[0].Transform(matrix);
doc.Pages[0].Size = new PdfSize(pageWidthInches, docLength);

byte[] pdfBytes;
using (var ms = new MemoryStream())
{
doc.Save(ms);
pdfBytes = ms.ToArray();
}