I know this is an old thread, but I have the same problem as @diggle .
The calculation for gross profit is wrong. I'll give short example.
In woocommerce settings, I have set to enter prices with VAT.
If the product price is 12EUR, VAT is 2EUR in my case (20%). If my purchase price is 4EUR, my profit is 6EUR, not 8EUR as your plugin suggests. Of course, I can enter a higher purchase price, and set it to be 6EUR, BUT that will make complete chaos if I give any discount, because the purchase price would be incorrect. That's why it's very wrong to calculate profit like that.
I know it's a free feature, and I don't have to use it, but if that's the logic you are using for doing very sensitive financial stuff, I won't buy premium addons, and I really intended to...
The only correct way to calculate gross profit is to reduce the sale price for the amount of VAT (if that option is checked in woocommerce settings), and then reduce it for the purchase price. There are no other ways to do that properly... Regarding affecting old installations, you can set one checkbox for all those who want to use the old way of calculation... It's really simple.
Also, on ATUM dashboard and product edit page you have div that is blocking the content. Complete Dashboard page is unresponsive, and on product page wordpress menu is working because div only covers product settings. When I remove it, everything works as it should (until refresh). I have installed/removed plugin twice...
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