Example: I have an audio track sent to a reverb. I want to hear only the effect, so I press Solo on the aux track, but the Solo button of the audio track gets selected automatically too.
Then I have two options if I want to hear only that effect:
1- Use the Listen button with the maximum attenuation in order to hear a real solo of the effect.
2- Turn the send to pre-fader and move the fader down, losing the level I had set.
It goes without saying it is annoying and makes no sense.