Audio Editor not showing everything

Hi there, the audio editor is not showing all parts of the track. So, one syllable, for example, can still be heard and seen (as grey waveform in the background) but there is no corresponding editable ‘block’ in the audio editor screen. I have scrolled up and down and there is nothing off-screen so to speak. Interestingly, some of these missing snippets are actually out of key too - suggesting a gremlin in the works somewhere. The clips which are not showing are only small parts (one syllable or so), but are clearly visible as grey waveform in the background. No obvious mistakes being made by me as far as I can tell. There are no hidden racks being played etc. This has happened on a couple of the tracks btw. Any pointers anyone? Tnx. Using 10.5.12.