Waveforms not showing

Nuendo 7. Nuemdo finds files fine, but when loading some waveforms dont show or play. If I double click the waveform I can see it in sample editor. If I reimport the same file it shows. Th gain is gain control on waveform makes no difference.

I have not yet fully understood the problem: is it just the waveform that is not displayed, or do you not hear any audio with such files without a waveform?

hi there is no audio either. But nuendo finds the wav and its in the pool. Reimporting from pool, it plays.