show us your query

When I tie the Staff Combo box to the query and go back to the client check out form all "Not_Active" Staff have vanished. If the staff combo box is not tied to the query they are there.

And by that I mean for past items which were checked out the Not_Active staff are not there. When using the query for new items being checked out only the active staff are in the combo box.

Are you basing the form off that query? It shouldn't affect anything in the form unless you have some event that's doing it or the record source is that query. Can you show the form?

This is what is there when the staff combo box is not tied to the query. If it was tied to the query all of those names would not be there. Not sure if it matters but this is a sub-form.

Oh and the sub-form is tied to the junction table not the query. The query is only tied to the staff combo box.

Not completely sure I'm on the right page with you here so just taking a shot,

So you're basing this form off a query where you limit the staff to only active? And then you're using the same query for the combo box? If so, that will hide all the records regardless of if they had ever issued something, the form should be based on the table with no query criteria to show everything that's been issued. The combo box can be based on the query where they hide staff that is not active. If this is not what you're saying can you send an image of the record source for the form and the row source for the combo box?

Sounds like an outer join issue

As of right now the subform is based off of a table and the combo box points to just a table called "Staff"; no query's. This returns all staff past and present on a client's record.

If I limit the combo box with a query showing just active staff then the staff combo field in all previous issued items goes blank and the combo box only shows active staff.

I want to see all staff who have issued items in the past but limit the drop down to only active staff.

Unfortunately, I believe this is one of those cases where you will need to store the Staff Member in a separate field for historical purposes.  Otherwise the Combo Box is doing what you have told it to do.  You can't have it one way for data entry and another for display.
It's a case of having your cake and eating it too.

To do that you could put an after update event in you Combo Box to set the value in the field.