Hi Sammies ,
Sorry for the misunderstanding. You didn't mention the dashboard in your first message, so I didn't think about the Dashboard widgets.
Please, try executing the "Update products' calculated properties" and "Remove ATUM transients" tools from ATUM Settings -> Tools. Does that fix the quantities in widgets?
If it doesn't, please check your server's PHP error log and tell us if anything is saved when you enter the ATUM Dashboard.
You can read here how to activate the PHP error log if you don't know how to do so.
You also wrote in your first message: "Also the orders have the wrong info". What do you mean? An example would help.
Best Regards,
José Andrés