Because it disappears and doesn’t show up again?
I had problems with the imlib2 thumbnailing too - I would suggest you to use Taviso’s thumbnailing method at first.
EDIT: I didn’t see that error message that imlib could not be loaded. Maybe try re-merging imlib2? It works fine for me with version imlib2-1.2.0-r2, and I’m on AMD64 too.