You name it and the excuse will be used, I could probably create a tick list for authors on what to watch out for. I even have the name of a good lawyer.
Seriously. Whatever the reason, lets be honest here. This is how it works.
Authors write books and publishers polish and publish.
Books are sold.
Publishers keep a percentage of money made on sales (after sellers take a bit, Amazon etc) as a way to cover costs and hopefully make a profit. Authors get whatever is left over.
The money that is the author percentage is for the author. However great or small that amount is, it is NOT PUBLISHER'S MONEY, it is author's money. They are merely holding on to it for us. If the publisher needs two months to sort out reports and holds on to the authors money in that time, if they only pay quarterly, hell if they only pay annually, whatever they do, they've had their bit and the remaining author money is NOT THEIRS.
The publisher should not pay for events, tax bills, the hairdressers, retreats, cars, houses, editors, trips abroad, cover artists, a cup of coffee, or anything else out of the AUTHOR MONEY.
Not one single author should ever have to say, "Bloody hell, I sold X number of books six months ago and I haven't been paid yet."
All author income should be held in separate accounts and every penny should be able to be accounted for with external audit if necessary.