I have noticed this too. chalkALPHA.dds modification does not affect chalks in game anymore.
Years ago I have created custom chalkALPHA.dds for our Caribbean Cruise server (now CLC). My goal was to change arrows from handmade chalk drawings to normal painted road signs, to be used for cruise layouts. And also change straight chalk lines to painted lines, without notches at both ends.
Modified DDS file was offered to our regular cruisers for download and overwrite original. Today when I modify it in Photoshop, LFS still shows originals. Tested with older LFS versions and it worked well there.
Is there any way to modify chalks again? Which DDS is it now?
Or is it inside the game now since the new feature of optional chalk colours?