I dont know is it best solution but for me helped. I changed one line on purshase.py

if purchase.invoiced_rate == 100.00:    to     if purchase.invoiced_rate > 0:

    def _invoiced(self, cursor, user, ids, name, arg, context=None):
        res = {}
        for purchase in self.browse(cursor, user, ids, context=context):
            invoiced = False
            if purchase.invoiced_rate > 0:
                invoiced = True
            res[purchase.id] = invoiced
        return res