Damage combos with push flags...

If you place a push flag on a solid damage combo, it can only be moved if 1. You do not have any item in the Boots Class, 2. You have an item in the boots class that does not protect against solid damage combos, or 3. You have a boots item that protects against solid damage combo, but all damage combos on that screen are set to ignore the boots.
If you have a boots item that protects against solid damage combos and the damage combos on the screen are not set to ignore the boots, then you would no longer be able to move any damage combos marked with push flags.