As far as I understand “Musical Mode” for audio clips can be activated only if a clip contains the tempo data. If it’s not (its means it has “???” in the Pool) then no Musical Mode for the clip.
I am working only with sound effects and MMode is very convenient for the fast editing right in the event display.
But I noticed one thing. For very short SFX (like 200ms) there is no posiibility to detect tempo and also to put it manually in the Pool window.
The only solution I found it is to add silence at the end of the file (i.e. make it longer) and then it will receive the tempo data.
I understand it can be really a minor problem but maybe it can be fixed in the future.