Graphical artifacts when animating scrollRect property in ENTER_FRAME handler?

Question

I tried to animate a drop down menu by assigning a rectangle to the scrollRect property of the menu.
The rectangle's width is fixed, and the height of the rectangle is animated from zero to the final height of the menu over a 250ms interval.
The alterations to the scrollRect originate from a master handler for ENTER_FRAME, which runs a series of registered task functions, one of which is my menu animation function.
As the menu drops down, various areas of the child DisplayObjects, including the background, fail to draw completely.  If I resize the stage at all, then everything is redrawn properly.
Are there any known problems with animating the scrollRect property when:
altering a scrollRect from within an ENTER_FRAME handler
when child objects also have a scrollRect set?
The exact regions that fail to draw are inconsistent each time the menu drops down, but they occur in the standalone player as well as in web browsers such as Firefox and Internet Explorer.
See video here: glitches2.mp4 - Google Drive
It clearly doing something wrong, as evidenced by the redraw regions at the end of the animation (see image).  At the end of the animation, the scrollRect is set to null.  The bottom of the menu is still not updated, and neither is the drop shadow filter on the menu.
Update: The artifacts go away if I set cacheAsBitmap to true: glitchesRemoved.mp4 - Google Drive
Interestingly, they also go away if I remove the dropShadow filter from the background child control and leave cacheAsBitmap off.
Anyway, this problem seems to manifest itself specifically when animating the scrollRect property of an object with cacheAsBitmap set to false that contains a child control with a filter applied.
Here is a final video with everything working.  The drop shadow filter is on the object itself, rather than the background, which sets cacheAsBitmap to true as a side effect:
glitchesFixed.mp4 - Google Drive

Answer 1

I'm just animating the scrollRect property to achieve a simple clipping effect that reveals the menu.  Once per frame, it updates the scrollRect property, assigning a new rectangle with a height of "p * height", where p is the percentage through the animation (0 to 1).  There is nothing, otherwise, happening to the DisplayObject during the animation of that property.  The DisplayObject's height is not changing, nor are any other properties changing (besides scrollRect), so it's essentially static while it's being revealed.  When the scrollRect's size is increased frame-by-frame, Flash Player is simply failing to render the entire clipped area, almost as though there is a frame lag such that it's rendering the clipped area from the last frame, rather than the new area exposed by the latest value of scrollRect.  When I simply turn on cacheAsBitmap, it renders correctly and completely.  The only "interesting" thing about the menu would be the DropShadowFilter applied to a child, so my best guess is that there's some sort of bug in Flash Player's rendering system involving scrollRects whose size changes when one or more child objects have filters applied (just a guess from what I'm seeing).  To fix it, I moved the DropShadowFilter off the child object and onto the menu itself, which kills two birds by forcing cacheAsBitmap on (removes the artifacts) and also ensures the drop shadow is applied to the clipped area rather than being clipped by the scrollRect.  I'd imagine I could replicate this easily in a simple FLA that I could post, so I 'll try that.
As far as the "sophisticated" nature of the framework, I was primarily referring to its layout engine, in the sense that it's non-trivial, finely-tuned, and powerful compared to existing offerings. There are no Stage3D effects; I ruled out using that years ago when I was seeing graphical artifacts throughout the display list whenever any 3D effects were applied (even setting DisplayObject.z to zero), because it seemed to change something about the overall rendering mode.  For example, I took these screenshots in 2010 and posted them to the bugbase:
What started off as a slight offset that appeared when 3D rendering was active, turned into very obvious glitches at the edges of objects, as revealed in the latter two images; the random speckles of color and the yellow lines at the bottom and right edges of the button are not supposed to be there. (The striped lines in the overall background are supposed to be there; they are part of a "circle splash" shader filter that collapsed in from the edges of the screen making it look like the background is being eaten by the event horizon of a black hole, haha.)
Anyway, the MenuTest.mp4 video I posted is actually using off-screen rendering to BitmapData via DisplayObject.draw, along with the application of a blur and tinting for the glass effect.  The real-time ripple effect is rendered with an animated ShaderFilter I wrote with PixelBender.