I'm not sure whether this is an actual bug or a feature...
If you set Visible to false for an object, and then animate it, the game hangs. Obviously you wouldn't want to do that, but my game was hanging and I found out I had forgotten to make my object visible before animating it.
At the very least, I think this should generate a warning at compile time or runtime, or maybe it does already and I didn't notice it?
PS: I saw this in v3.3.4, build 3.3.4.2.
It probably hangs because you are doing something like while(object.Animating)?
It's a known bug that was never fixed:
http://www.adventuregamestudio.co.uk/forums/index.php?issue=509.0
It was a blocking animation, which is probably equivalent. Thanks for the info.