When used as an effect send in Logic, the Spring-636 does not respond to automated send volume when song is played back the first time. It only responds when song is played the second time and afterward.
As an example, let's say you want a blast of reverb on a single snare hit. So, you set up an effect send which contains the Spring-636. Then, you draw an automation on the snare track which sends a single snare hit to the reverb. But... the reverb will not respond to this automated send the first time the song is played back. It will only respond during the second, and subsequent playbacks.
I am seeing this issue with Spring-636 1.2.0