Sorry to leave this post under Comp FET-76, but most of the FX Collection 2 plugins do not have their own sections in the forum, and I cannot see a way to create a new section for Spring-636.
The problem with Spring-636 is that Arturia's Undo arrow does not light up (is not available) after adjusting just one parameter. The Undo arrow only becomes available after making two separate parameter adjustments.
Perhaps this is happening with other FX Collection 2 plugins as well (?), but I thought I should at least report this one, as I just encountered it while using the (fantastic sounding) Spring 636.