I am trying to play with Contracts module. I entered 2 contracts for the same client specifying dates in the matrix as per manual (from 2018-08-01, to 2018-12-31), then generated an invoice for the period from 2018-08-01 to 2018-08-31 using the maintenance with "Factoring Customers Invoicing" ticked. Everything was OK. Then I unOked the second contract and added one more row with dates from 2018-09-01 to 2019-08-31.
The problem is I cannot get the second row with dates from 2018-09-01 to 2019-08-31 invoiced. The first row is always invoiced as it should while the second row is never invoiced and last invoice date field in the matrix is empty.

What I have done wrong?

As far as I understand the maintenance should simply find not invoiced row in the contract and simply invoice it