Reading a lot of reports about how arbitrarily this is being enforced.

Reasons people have been made to pay $100:
- It doesn't slide all the way into the sizer without pushing
- You can only give it one push
- It can't touch the sides of sizer
- The bag has wheels, even if it fits in the sizer
- Item fits nicely, but bag handle/strap sticks out slightly

Seems like with all this going on, best not to fly Frontier for the time being until things calm down.