Frame rate of the imported media

Hello,

I'm making a video tutorial about using a software. I made several clips (30fps) and I want them to combine and edit in After Effects.  My voice is in the separate audio file which will be combined with the clips.

So I filmed what the mouse pointer is doing. However, there are moments when the mouse pointer is standing still for couple of seconds. Those moments are reserved for some explanation.

I've noticed that when I import the clips in After Effects, the frame rates are different. So I used "Interpret Footage" and set them to 30fps. Now, everything played fine but those moments where the mouse pointer is standing still are treated like 1 single frame.

Why this becomes one single frame? Is there any way to import the media without loosing the full duration of the portion of the video where there is no movement?

Thanks