Illustrator file not importing correctly into After Effects (CC 2018)

Had the same problem. Seems it occurs if multiple artboards are in play. 
Remember to save your art in different layers on the same artboard - this fixed the problem for me and made it possible to switch between layers when importing to AE.

I had this problem as well turns out I had multiple artboards and elements outside of the artboards. So I removed the extra artboards and made sure everything was within the borders of the artboard.

1x1 means possibly the Ae thinks the layer is blank.

make sure you read this carefully and follow the instructions on how to prepare your Ai files to Ae:

Preparing and importing still images in After Effects

especially the artboard section.

Without better info about your file by ways of e.g. a screenshot of the artboard and layers palette nobody can tell you anything. there could be a million reasons why it's behaving like that.

Mylenium