Maintain Layers for Illustrator Files

I'm trying to import an Illustrator file into Corel. However all of the groups become ungrouped when I import.

Illustrator Groups:

Corel Ungrouped Layers:

I found another AI file that has groups and imports them fine into Corel. I just don't know what the difference between this AI file and the other file that can open correctly.

Illustrator:

Corel:


C4 Energy file - https://ln.sync.com/dl/efce7f000/fwgahjgx-jfghctyr-jmh6ri6i-pi7pxz4n 

Fireworks - https://ln.sync.com/dl/09b6bdae0/5uwprhz3-kx4z4qun-57e4gc6p-t9t6fp9b 

Is there a setting in Illustrator that preserves groups?