Playing audio gets stuck

Hi,I am making a shooting BP,and I play the fire sound every time shooting.
I use delay node to handle cool down time.
when the fire rate is less then 0.1 second, the sound playing will be like “aaaaaaaa——aaaaaaa——aaaaaaaa” ,not continuously playing.

I never met this before. I used to use more less delay like 0.02 it still worked at previous project.
But this time I have no idea what to do.
Please help,