Why are some MRP jobs associated with an order where others are not?
I’m guessing the MRP job is associated with an order if we don’t have stock to fill the order, and MRP jobs not associated with an order indicate they are replenishing stock to min on hand levels.
Look at the Make to Order flag on the sales order
Non-stock parts (part master non-stock checkbox is checked on the site tab) that are added to a sales order will automatically be checked as make direct on the order line release. MRP then knows that the part is to be made direct/made to order and will populate the demand link as make to order on the associated job
Confirming that @mjfwagner & @JimA are both correct… if the job is created as associated to a sales order, then that sales order was marked as “Make Direct” on the sales order RELEASE. Note that this will automatically be set to TRUE if the part is a non-stock part. BUT if the part is a STOCK part, the user can still override the setting and force it to make Direct on the release (which will also show it as an OVERRIDE on the release).
Note also, that this same thing can happen in a JOB. You can go to a manufactured Material line, and mark it as Make Direct, which will cause a Job-to-Job demand. You will get a second job to manufacture the material and its tied directly to its demand job.