In juce_DrawableButton.cpp, setImages() calls copyDrawableIfNotNull for each Drawable pointer.
However the size of the Drawable component is not copied to the Drawable member pointer.
This leads to Drawable components with a zero size. As the result the button can disappear when turned on...
I modified copyDrawableIfNotNull to copy the size of the drawable component into the new one and it fixes the problem :
static Drawable* copyDrawableIfNotNull (const Drawable* const d)
// old code
//return d != nullptr ? d->createCopy() : nullptr;
// new code
Drawable* pDrawable = nullptr;
if(d != nullptr)
pDrawable = d->createCopy();