Beeping out portions of an audio file using ffmpeg

I'm trying to use ffmpeg to beep out sections of an audio file (say 10-15 and 20-30). However only the first portion(10-20) gets beeped, whilst the next portion gets muted.

ffmpeg -i input.mp3 -filter_complex "[0]volume=0:enable='between(t,10,15)+between(t,20,30)'[main];sine=d=5:f=800,adelay=10s,pan=stereo|FL=c0|FR=c0[beep];[main][beep]amix=inputs=2" output.wav

Using this as my reference, but not able to make much progress.