I used /fill to make dragon eggs go through the end portal, and when I hopped in, I couldn't move, but there were NO dragon eggs in sight. Then, the game threw me back into the Overworld. However, when I did it with ONE dragon egg, the egg appeared in the end.
Steps to reproduce
1. Make an end portal
2. Fill the air above the end portal with dragon_egg, not counting the 3x3 layer of air directly above.
3. Repeat with only 1 dragon egg.