Well, I was trying to make a really cool effect that I know as "Metaball". Its not my first time doing it, but its the first time after some Illustrator updates, so I just wanna check if it's a bug.
The efect create some sort of "liquid" form, like the things floating in a lava lamp. The steps are:
- Create two objetcs (circles most of the time) one near to each other, and one of them smaller
- Make both objets a Compound Path
-Aply an Offset Path effect with rounded joins
-Apply a Outline Stroke effect where que offset is the same as the offset path but negative, with rounded joins to.
And thats it. But the menu for the outline stroke just doesnt appeare to me anymore 😞

This is the appearance structure. The first offset path effect is positive, the second negative:

You can apply it to a compound path rather than a compound shape, but you get a negative effect when objects intersect