Argentina Cumulative Withholding Tax doesn´t work properly

Hi Buddies.

Someone knows  reasons why or where take a look Cumulative Argentina WHT doesn´t work properly.

The scenario is the following, there is a vendor which has already applied a WHT but in the following payment done, the Withheld amount calculated is "0". for the same period.

if the mínimum taxable base amount $30.000 and there were payment which has already calculated the WHT, why the following payment for the same vendor and period retrieves "0" withheld amount?

thanks in advance