Here’s the way around the “can’t-automate-the-mute-send-button” in LOGIC Pro feature, and I don’t know why I didn’t think of it before, here goes:
1) For the sake of example, route send 1 to bus 50
2) send the output of bus 50 to bus 51
3) Stick the echo plugin of your choice on the insert on the sub out channel that hosts the output of bus 51
4) Now by automating the channel mute on the sub-channel of the output of bus 50 you can control the signal going into the echo as an automated, rhythmic sequence.
Basically all you’re doing is adding an extra stage (bus route) to a send output and using the extra bus in the middle to control the output to the echo or plugin of your choice. And works great!
I used this technique on my tune “Red Cat” https://soundcloud.com/kevin-atwood-composer/red-cat