I'm having the same issue since one week, in Odoo 10 (community). Scheduler calculates stock purchase, but doesn't book/reserve available stock for delivery orders. Like paulvo wrote, only thing that works is checking availability manually for each delivery order. When clicking on Book (Reserveren in Dutch), the items for the delivery become available.
I've tested this in a backup database from just over a week ago, running on the same server. In that backup the scheduler still updates availability for delivery. A new backup from my live database on an other server keeps having the same issue.
I've tried resolving this by using the upgrade button for the procurement and JIT apps, that made no change.
Does anyone know what I can do to resolve this?