some problem about sfxPlayOnce(),help!!!

I creat a music play, use the sfxPlayOnce() function like that "$client::BackMusic = SFXPlayOnce(AudioLoopGui, getSelectBackMusicPath());" and use "fxStopAndDelete($client::BackMusic);" stop play music and release the memory. But I found the release function do not work, the memory continuously enlarges.

someone help me please!!!!