I think I've seen this occur when there are things like very short lived processes that all in combination use a lot of the CPU. This bit of documentation shows which processes get displayed and if it doesn't meet at least one of these criteria they aren't shown:
Hi James. Thanks for the information. I've seen on this machine that a process will consume 100% CPU for 30 minutes. Wouldn't that meet the criteria of the following?
Processes for which one of the following conditions is met for at least 3 of the last 5 one-minute intervals: