What's a missing amount for an allocation?

Missing amounts are listed only on subsequent allocation generation when the allocation uses an incremental method.

For example, if a project was closed from the previous allocation generation, then the amount that was previously allocated to the project is listed under the Missing Amounts tab, though the project does not receive any further allocation transactions. The application tracks the missing amounts so that the source, target, or offset amounts are accurate. Example reasons for missing source amounts are: task is closed because the task is complete or the task is excluded from the source line.