Are you using the optical output of your motherboard? If so, this is an inevitable, well-documented bug and has nothing to do with drivers or mobo.
The spdif signal goes to "sleep" automatically when no sound is played, and the next sound will miss the first 500ms while it wakes up.
I've installed a little utility that prevents spdif from "sleeping". See:
If you're using analog audio, then the problem lies elsewhere.
EDIT: Sorry, I'm actually using THIS tool 😄 https://veg.by/en/projects/soundkeeper/
Our tech team have tested the components on hand, but didn't encounter the same notification sound cut off issue.
Do you have the issue right after you install windows?
Because our tech team have tested with new windows installed, but didn't reproduce the issue.
Could you please backup your personal files and reinstall windows to see if it still occurs without other apps?