Hello Deepbass,
some playmodes like 'formant' or 'vocoder' or the modes with 'key' in the name use keytracking. The keytracking modes can not be rendered to a single wavetable, since the sound does change dynamically and does depend on the current pitch you are playing. You still can perender such a mode, however it sounds different from the original, depending on the current note you are playing.
For previewing and prerendering wavetables you should select one of the static modes like 'harmonic' or 'hollow'.
You can find a more detailed description of the modes in the handbook.
Best Regards,
Markus