Hello
I’ve been trying to animate my filter mask opacity in the animation curve environment.
I created a layer, added a filter mask (gaussian blur) and grouped the filter mask with the paint layer. then I keyed the filter mask in the animation curves and animated it from opacity value zero to 100. but I don’t see any changes in the animation.
Am I approaching this the right way?
I don’t think filter masks are animation aware. Use Filter Layer instead. You can put it in a group alongside another layer to get a similar effect as a mask.
Hello and welcome to the forum 
You don’t need to do that because a mask is locally ‘attached’ to a layer and only affects that layer.
The GUI of the Animation Curves docker lets you do that as it does for transparency masks and paint layers. However, that has no effect on masks.
I think this is a GUI bug.
You can manually animate a filter mask and a transparency mask by traditional painted frame by frame animation methods.
Also, you can convert an animated image sequence into a filter mask or a transparency mask (and vice versa) so that can be used to create structured transitions.