Does it occur in multiple commands in your profile? If so, only when modifying existing commands, or even when creating a new command?
I added a "Block Mouse Input" to the "Mouse Click 56" command, then drag-and-dropped it, which causes no issues on my machine.
What you could try is to make a backup of the profile database by clicking the "Click here to browse VoiceAttack's data folder." link on the "System / Advanced" tab of the VoiceAttack options window and making a copy of "VoiceAttack.dat" in a safe location, import the profile you've already exported, then see whether the issue still occurs in the imported copy.
As an aside, rather than creating multiple variations of that command, you could retrieve the spoken number from the command phrase.
E.G.
Mouse Click [5;10;25;50;56;90;180]
Fully restrict mouse movement
Play sound, '{VA_SOUNDS}\confirmation_beep.wav'
Start Loop : Repeat [{CMDSEGMENT:1}] times
Click left mouse button
Pause 0,1 seconds
End Loop
Unrestrict mouse movement
Play sound, '{VA_SOUNDS}\confirmation_beep.wav'