There seems to be a pattern with changes that can not get a change log.

If the build is triggered and placed in a queue for building, and meanwhile another build is taking a long time in that queue, then changes made to the code during that time period will not retrieve changelogs.

In the following scenario:
LW-NIGHTLY - runs for approximately 2.5 hours, scheduled build
LW-COMPONENTS - runs for approximately 15 minutes, polling build

LW-NIGHTLY is triggered to run. Meanwhile, a change (CHANGE-A) happens that would cause LW-COMPONENTS to build, so it queues up a build. CHANGE-A is correctly recognized. After LW-COMPONENTS is queued, another change happens that would cause another build (CHANGE-B). When LW-NIGHTLY finishes, LW-COMPONENTS does its initially queued build (containing only CHANGE-A). Then it performs a cvs update, sees a file changed, and attempts to get a changelog. The changelog retrieval for CHANGE-B seems to be using an incorrect timestamp (that of the time the prior build began, not the time the prior build was queued), so any changes that happen between queue time and build time are lost.