I've attached some screen snaps of my PP results for Ilford Smooth Heavy Weight Matte, Epson R800 with Epson ink, for you to compare. I guess the paper is similar to yours.
The PP reports are actually quite good.
However, you can see on the printer target histogram particularly, that there is a gap at the LH end. This resulted in poor detail in dark shadows on prints. I assume my Canon 8400F scanner, with Vuescan, could not cope with the darker patches on this paper.

I did also buy a "professional" custom profile for this paper; it was better but shadow detail was still limited so I assume that's the limitation of this type of paper.
Did you try any prints with your profile?
(Click attachments to see full size)
Terry.

[/quote] Where are the X's occurring?  If they occur on mostly white and very bright colors, your scanner may be overexposing.  If they occur on saturated colors like bright magenta, bright green, etc. your scanner my be oversaturating.  What scanner are you using and what software to acquire?

Mike
[/quote]

Thank you both for a quick response. The X's are occurring mostly on the 1st line, more on the left hand side ie patch 0 onwards.
The scanner is Canon  MP970 (AIO). The software is Vuescan with settings as recommended.

I did make a print using the profile obtained. It's OK but lacks a bit of details.