I have a case similar to @milagros.limahuaya, only that with quantities of kilograms in the products, in a purchase order it does not generate an invoice and the following message appears:
I go to the Kilogram UoM configuration and have it configured like this:
This purchase order must register 2 invoices, once I make a single invoice with an amount less than that of the purchase order, Tryton must generate another one with the remaining amount, but in this case it does not generate a subsequent invoice, because the message posted above.