question

If you set the model run speed to 0.0, hit reset and run, and then hit step twice, you'll see that a back order is created requesting 6 operators where there are currently no entries on the list. Hit step one more time and you'll see that all of the entries are then added to the list with their opAvail field empty. Hit step 5 or 6 more times and you'll see the opAvail field be filled in with 0's. Eventually they become available.

It's important to understand when a back order is evaluated. When you first pull from a list, it goes through each entry and tries to pull that entry based upon the criteria set in the query. If it can't complete the pull request, the back order is created. Now, each time a value is pushed on to the list, that back order is reevaluated for THAT entry only. It does not reevaluate for every entry on the list (this would be slow). Since the pull happens before the entries are on the list, and when the entries are added to the list, their opAvail field is not 1, the back order never fulfills. If this happens, you have to tell the List to revaluate back orders. This can be done through the Back Order Reevaluation Events in the List properties.

The other alternative that may work depending on how your model is set up, is to ensure that the first pull request does not happen until the entries are on the List.