On the CDJ-850, there are a number of problems with the waveform display when playing CDs:
1) When you play a CD track, the waveform rarely builds. When it does attempt to build, the following problems also occur
2) Sometimes it just builds a solid bar (as if the track is peaking the whole time). This renders the waveform display as useful as the progress bar underneath.
3) It often only builds in real time (this is ENTIRELY USELESS, as I can HEAR what has happened in the past in the past, the waveform is to give an idea of what will happen in the FUTURE)
4) On occasions when it does scan ahead, it stops halfway through, and then does not proceed
Before you tell me, I know that if I analyse the tracks first using the Recordbox software the wave display is more reliable (usually, not always). However, for the working DJ this is not always practical. If I'm given a new track on CD, I don't always have the time/will to copy it onto my computer and pump it through Recordbox. If I want to use software, I can use Traktor. Sometimes you just want to turn up to the venue with your latest racks and play them. When you see CDJ-850s at the venue it makes you shudder.
This is an issue that needs resolving immediately. The bulk of DJs/clubs/bars who buy this product will do so with a view to playing CDs, if not all of the time, at least some of the time. Otherwise they would purchase Traktor/Serato + controllers. The wave display is one of the key features for this purpose, and one of the reasons why upgraded from my CDJ-800 Mk2s (a decision I will regret if this issue is not resolved).
I am using the latest version of the firmware (1.06).