If you drop an audio file into the project from media Bay or anywhere else…
Does the waveform display for that ‘part’ show correcttly/as expected…?
Am I right in thinking the waveform your describing for the recorded part in question is ‘very flat’ with not to much vertical up and down ‘waves’…?
Without stating the obvious it’s not just a case of a very low level/weak signal…
If your recording levels are very low the display would appear very ‘flat’… And with extreme zooming in you’d then get some visible ‘up & down’ lines…