Classic tweening along scaling guide does not work properly

I am trying to create an animation where symbols follow a scaling guide across the screen. The symbols will begin invisible (Alpha: 0), then become completely visible (Alpha 100) about 1/3 of the way across the guide. At 2/3, the symbols will once again become transparent, fading into invisibility again at the end of the guide.

The guide is set up (a straight line with Width Profile 1) so that the symbols get a little larger as they go across, then smaller as they reach the end. Pretty simple.

Here's the problem: In the animation that I'm trying, the symbols stop 2/3 of the way across and disappear. The first 2/3 of the guide perform as intended, but the last 2/3 do not function as I said. The odd thing is: the animation works perfectly on the stage. Nothing seems amiss. But when I export or test the scene, the malfunction occurs. This is so bizarre. I've done scaling guides exactly like these before without issue. The ONLY animation that works as intended is the one animation that is nested just below the guide layer. Even though all the other layers are also nested underneath, ONLY the one just underneath works correctly when testing or exporting. The others nested under the guide malfunction as I stated.

Does anyone have any suggestions??