Ok, here's what I know, BUT please keep in mind that what I will write will be a mix of information received directly from a trusted friend who worked with her, a message relayed from a model whose friend worked with her, and from herself (Harper Maddoxx it self) during her coffe talk with model I really, really trust.
The contracts she arranges are probably arranged by someone else (it's not fully confirmed but a couple of elements point to it). This means that a producer who contracted with her, for example, for a "dildo" upon her arrival is put in the situation that she knows nothing that there was to be a "dildo" and that she will not make a scene with a "dildo." This situation - literally that she knew nothing about the content of the correspondence regarding the elements of the planned scenes (to which she agreed) took place.
So there is no question of simply cancelling the cooperation - which in ethical porn she obviously has the right to do - only that the ordered service will not be performed and the producer is cheated from the very beginning of contracting.
Another situation is that after one day of shooting she reportedly feigned illness to avoid coming to the set. Another time she arrived but moved to a hotel where she has to spent a few hours and then go to the set. Instead, she fled the hotel leaving the producer with nothing (I don't know completely but I guess the money was also gone). Guy arrive for her but there was no one already in the room.
Note that there is a difference between cancelling a contract (I repeat the statement that in Ethical pornography this is a natural thing), and simple fraud. Imagine the situation that you rent a studio room, rent an apartment for the model, pay her ticket, organize your time, arrange the paperwork for work permits and.... and the model simply does not show up and does not justify why. Imagine the situation that, in addition, something like this happens when two models are supposed to appear and the only sense of the whole scene is they both at once and the latter arrives. Now what if the first one didn't show up or ran away? The second model who arrived is to be left without payment or what?
I understand that this is a producer's risk, but think about it after all not everyone is Brazzers etc. There are quite a few people who barely make ends meet. It is very difficult to act ethically and at the same time make a living with so much unethical competition.