The same way I did in the
post about the UNDUPE.CAL bug, there is a bug in the
LEGATO.CAL script.
It happens specifically when you try to run it when there is a note selected at the 0:00:000 time. In this case, this note is shortened to a minimum and in addition, the script "forgets" to delete a series of additional controls (C0 notes).
To confirm this, download
this MIDI file, open it with Sonar, activate the Event List (Alt + 8), select the entire track and run LEGATO.CAL (Ctrl + F1).
You could see the results I'm mentioning.
In this way, I created a revised version.
You can download the script at Github.