You can apply both color (tint) and alpha changes to symbols (Movieclips and Graphics) but you have to do them separately - there need to be two timelines - one symbol is inside another symbol. You control the opacity on the parent symbol and the tinting on the child symbol.
So you need to make a graphic symbol - let's say a blue circle by creating a circle and creating a symbol of it (F8) and giving it an instance name - "blue-yellow-circle" - click "OK".
While "blue-yellow-circle" is still selected on the stage, make it a symbol again (F8) and give it another instance name - "opaque-circle-transp". So now you have a graphic symbol inside another graphic symbol.
Here's the structure:
Each symbol has a timeline, just like the stage or root. So now you need to create an animation in the "opaque-circle-transp" symbol by setting the "blue-yellow-circle" symbol's tint. So let's say you make the animation 30 frames. You can leave the 1st keyframe alone - i.e. no tint. Create a keyframe at frame 30 and set it to a particular tint. Now create a "Classic Tween" between these keyframes by right-clicking in the frames between the keyframes and selecting "Create Classic Tween".
Now go to one of your keyframes (1 or 30) and double-click your circle symbol. you should now be within the symbol "blue-yellow-circle". Create a keyframe at frame 30 and designate the alpha to what you want. Now create a tween by right-clicking and selecting "Create Classic Tween".
You can now go out to the root or stage level and you should still have 30 frames. Now if you test the animation, the symbol should transition from blue and opaque to yellow and transparent.
An alternative to this would be to use shapes (only if the shapes are fairly simple and similar shapes). You can do this all in one timeline if you set the color and opacity of the shape for each of the two keyframes and create a "Shape Tween" between the keyframes.
I hope this is helpful.