For some reason any time I import an image and create a new layer with a vector layer already opened, the vector lines no longer work. They become ridged again. Is this a bug or am I doing something wrong?

When you 'create a new layer', are you sure that you're creating a vector layer? If you press the '+' icon at the bottom of the layers docker, it creates a paint layer and makes that layer the current layer (highlighted as a blue colour) so any paint/draw tools will produce raster (non-vector) strokes. In the layers docker, each layer has a small symbol to the left of the layer's name that indicates which type of layer it is.

To create a vector layer, press the small 'down arrow' icon next to the '+' icon and choose Vector Layer from the options. That new vector layer will then become the current layer and will be highlighted as blue.

If you still have problems, please give more details of the steps you took leading up to the problem and also a screenshot. You can use Imgur and similar image posting sites then put the link in your post.

No I mean I have a problem importing an image and drawing over it with a vector layer. The vector layer itself won't work as vector and still has ridged edges so I am asking what am I doing wrong? What can I do to draw vector graphics in this program?
I made a demo. of what I mean: https://www.youtube.com/watch?v=m80MavCS6tQ&feature=youtu.be

Also Krita just crashed twice when trying to record a demonstration. All I did was undo a few times and open new canvases.

With an image size of 800 x 600 at 400% zoom, you are very close to seeing the individual pixels of the image projection onto your canvas area. If you zoom in a little bit more, you will probably see them outlined.

What you see in your video is the vector line being constructed at the screen resolution, then placed on the canvas of a fairly low resolution image. This will happen every time with a vector layer of that size at that zoom level, no matter what other image has been brought in to Krita. It's still a vector object and can be manipulated as a vector object but the image you made can only represent it within the resolution limits of an 800 x 600 grid of pixels.

If you create a new image of 1600 x 1200 and try this again, you won't see as much pixelation of your final vector shapes.