I have a Particle Illusion (PI) effect on an event.

Trying to animate the emitter offset, which I've done plenty of times. But new for me is trying to use Bezier CURVES to smoothen the motion -- SO HAPPY to finally have realized I can do this?!!

But it's not working right.

I add the keyframes, right-click a point on the Emitter Offset lane to set it to "Split Tangents" (I can't just set it for X or Y), change to "Curves" view. Sometimes it doesn't show me handles. When I recorded this video the handles showed BUT nothing can be manipulated. I can't move the handles in the curves view... can't move the points there either. Obviously, if I can't move the handles, they do me no good!

Is there a "Lock Handles" button I've missed somewhere?!

NOTE: I added a Vegas Picture-in-Picture effect and I'm able to manipulate the curve handles on that just fine.

NOTE 2: In both cases, after choosing "Bezier split tangents", the UI doesn't place a checkmark next to the selected option, so it's not really clear if my change actually "sticks"