Activity ID, makes it to the task table , but not to the project activity table. Why?

There are some users who sporadically when creating a work order, the activity id is created and placed on the work order task table, but that activity id isn't making it to the project activity table. Therefore, when there is an attempt to create a purchase order linked to the work order itself, it fails. The error message is because the activity id doesn't match. "PC Business Unit - Project - Activity combination is not valid. Please, select a valid combination."

This is only happening sporadically. But it is frequent enough to cause concern.

Has anyone else seen this issue?