alsaDevice.PlaybackVolume can not work correct

[willhuo]

step 1 to 3 is time sequence
step 1:set alsaDevice.PlaybackVolume=100,it can work ok
step 2:set alsaDevice.PlaybackVolume=20,it can work ok
step3:set alsaDevice.PlaybackVolume=100,it can not work correct;when i get alsaDevice.PlaybackVolume value,it is 20.

os centos7.9
docker deplay