Try this:
If you don’t already have “FFmpeg for Audacity” installed, follow the instructions here to install it: Installing FFmpeg for Windows - Audacity Manual
Then in
“Edit menu > Preferences > Import / Export > Extended Import Preferences”
Click the “Add new rule” button, and name the new rule: *.mp3
Then in the right hand column, move “FFmpeg-compatible files” to the top, like this (below), and then click the “OK” button.
The drawback of this method is that MP3s will be imported as 16-bit tracks. It is highly recommended to convert the track to “32-bit float” format immediately after import (see “Format” in the track dropdown menu: Audio Track Dropdown Menu - Audacity Manual)
