Solved
Live 12 latest version. Had this problem before but forgot the fix.
I have a single audio track. It plays in Live ok. (waveform is there)
track 1 is on (not muted). Extern = Main
Volume level is up (at 0) and registers sound.
export to WAV
rendered track Main
start and length are good 113.1.2
sample rate 44100
PCM encode PCM , file type WAV
bit depth 32
EXPORT creates a file 78,123 KB
playing it is silence