Hi Chris,
You’ll probably find it better to keep all your plugins active (i.e. not disabled), and instead mute the MIDI routes to them in your different song states. That means when you switch states, any held notes or envelope/reverb tails from the last sound will continue into the new state instead of being cut off.
Also note that if a plugin is disabled, it’s not going to change sound - it’s effectively asleep. This is another reason to keep the plugins active, and I think that’s maybe the cause of the problem you’re seeing.
There’s another thing to be aware of that might get in your way. The way patch changes work depends a little on the actual plugins; some will respond nicely by just changing the preset in Cantabile’s drop-down for each state (as long as state behaviour is set for “Selected program”, in the state behaviour list). But for some plugins this won’t work - they only deal with a single internal preset, rather than a bank of presets you can select between, and so you typically need to set “Entire Bank” state behaviour instead of “Selected program”, which means that Cantabile will store the whole plugin state for each song state, and reinstate it when changing song state. From memory, I think Absynth might be one of the plugins you have to use “Entire Bank” for - in which case, every time you save the song state, Absynth’s state will be stored in the song state, and you’ll operate that way instead of via the preset drop-down.
Hope this helps,
Neil