From Jeffrey Morlan: pst_build_id_ptr and pst_build_desc_ptr require that the first child of a BTree page have the same starting ID as itself. This is not required by the spec, and is not true in many real-world PSTs (presumably, the original first child of the page got deleted). Because of this, many emails are not being extracted from these PSTs. It also triggers an infinite loop in lspst (a separate bug, also fixed)

--- a/src/lspst.c	Tue Dec 22 08:59:46 2015 -0800
+++ b/src/lspst.c	Wed Jul 06 10:12:22 2016 -0700
@@ -137,8 +137,8 @@
                 ff.skip_count++;
                 DEBUG_INFO(("A NULL item was seen\n"));
             }
-            d_ptr = d_ptr->next;
         }
+        d_ptr = d_ptr->next;
     }
     close_enter_dir(&ff);
     if (result) free(result);