A couple of "bin tips" that many know....so I ask the PE's and jillion-milers to forgive the repetition:

Try puttin in the roller handle first.

Try it handle first and upside-down.

Get a pillow or blanket and make a little "shim" at the front of the bin. That will often lift the "obstruction" at the end of the bag into the curved part of the hatch.

Look for the bins without a "lip"....they do exist.

Finally....board early and put your bag in lengthwise -- and let the other fellow figure out how to close the hatch when he turns it 90 degrees. (Only kidding....gotta be a good "bin citizen")