I get to see this weird border in the glow of my spheres at certain frames, but only when the camera is turned on. It's not on the edge of the layer, as far as I understand. I'v tried to see where it comes from by turning effects and layers on and off one after another. It disappears when I turn off the glow effect, or change the settings, but I don't want to do that. Also, and most importantly (I suspect), it disappears when I change the blending mode of the two sphere pre-comp layers from "normal" to "screen", but I can't have that as well, though eventually I may be forced to duplicate the layers and trim them here and there so that I can render the "screen" blending mode version only on the problematic frames, as I understand that blending modes cannot be keyframed. But I'd hate to do that... there must be a better solution, don't you think? Or even if I approach the issue with duplicating, I understand that I can regulate which layer is rendered when with the help of expressions, but I don't know where to begin there, I have very little understanding of expressions at this point.
So... any educational ideas?
P.S. (Now that you're already here...) I can't rasterize these pre-comps of course, perhaps that is part of the reason of why the spheres look so blurred. Do you happen to have any suggestions on how I could improve the quality in this particular setting? (The background is fine, this frame is just motion blurred.)
Cleaning the cache didn't change anything, I haven't moved the camera in time at any point, and changing the order of the effects doesn't resolve the edge issue but messes everything else up. I think your second suggestion is very likely. You see, the two spheres are separate pre-comps, and they are parented to a null layer that rotates, and the camera pans around it from the side to the front. So, yes, the layers are slightly rotated, in 3D space, and the glows of the spheres are intersecting.
Do you think this visible edge phenomenon can be fixed?