The sound doesn't work and you can't even see the waves.

Good time of day. I recently downloaded DaVinci, but for some reason the sound doesn't work in it. Even the sound wave is not displayed. I uploaded the video in mp4 format. There is sound in the video. All settings are standard, as when downloading.

Which Resolve version? Free or Studio? Edit page or Fairlight Timeline?

MP4 is a container format. What is the source audio and video codec?

Use MediaInfo to inspect the source media.