It's likely to be a process problem rather than the paper itself.
It may be that in some cases the Baryta layer is becoming damaged, this is the white layer below the emulsion, this will happen with prolonged washing, usually if prints are left a few hours in water (typically overnight). It's also highly likely that the high pH of Lith developers might acerbate this so it's important to keep the total wet process cycle as short as is practical & safely possible for archival reasons.
I have had problems, but they have always been of my own making, forgetting to take prints outof the wash, leaving them overnight, and sometimes through the next day, But with good archival washing, & use of HCA to cut the times these problems shouldn't occur.
Ian