Why can I no longer hear any notification sounds on with the sound turned all the way up?

[DotLGphn]

For some reason, I'm not able to hear notification sounds on my LG Stylo 6 phone especially when I try to choose a different sound, I can't hear what they sound like. I have my volume turned all the way up. I've already restarted my phone.

 

[mustang7757]

Stock sounds or custom?

 

[B. Diddy]

Do other sounds work, like if you play a YouTube video?

Does this also happen in Safe Mode? https://www.lg.com/us/support/help-library/lg-android-safe-mode-CT10000025-20150110993235