Poor image quality from vector assets saved in my library

Hi,

I have saved a number of logo and vector assets to a library, which is now appearing with Adobe Express. When I add them to the page they look low resolution and cannot be scaled up. 

Surely if they are Illustrator assets they should be scalable without any loss of quality?

I have also tried ensuring that the asset artboard size is much larger than the destination artboard size. No matter what I do they appear the same when added to the artboard in Adobe Express.

Anyone shed any light of this?

Cheers, Adam