ImageView setImageBitmap does nothing inside complex layout inside onTouch, intermittently

Question

I have nested layouts with ImageViews inside. These are all inside a ScrollView. Initially, the ImageViews are set to a Drawable resource.

I used this solution to detect scrolls. It's called from inside a onTouchListener(). Android: Detect when ScrollView stops scrolling

Inside the scroll listener, I update the ImageViews to load Bitmaps from files.

There are times (about 1 in 10?) where the setImageBitmap does noting. The Drawable resource is not replaced.

I tried the following: * requestLayout() after setImageBitmap() * invalidate() after setImageBitmap() * posting the ImageView drawing logic to the UI thread separately