Allowing Ordering of Out of Stock Products does mean product is in stock

[wrequine]

I apologize if this topic has been discussed before, but after much searching I have not found a solution.

 

PS version 1.6.1

Theme based on a copy of Default-Bootstrap, no core modifications

 

Situation:

I allow customers to order out of stock products in my shop, which are either then shipped direct to the customer, or ordered by me for the customer.  All my in stock products are usually shipped the same or next day.  The system works as it should, and customers are not confused, because the product labels are set to display "qualifies for same day shipping" on in stock items, and out of stock items are labeled "Usually Ships in 3-6 Days," "Ships Direct," or "Please Contact for Availability," depending on the product.

 

I had set the translations in Layered Navigation to match those of the product quantity labels - specifically, I changed In Stock to "Qualifies for Same Day Shipping," and Out of Stock to "Available to Order."  Everything worked as it should, until...

 

It seems that more recent versions of PS equate allowing orders of out of stock product with the product actually being in stock.  So, when enabling the layered navigation availability filter I see 0 out of stock products, and everything is in stock, which is not the case. The same is true for the filter at the top of the product list page.

 

I'm not sure exactly when this issue arose - I think it was during an upgrade to 1.5, or around there somewhere.  I searched extensively and was unable to find a solution, so with other more pressing issues at hand, I disabled the filters and put it on the back burner.  Now that I have upgraded to 1.6.1, I am looking for the solution yet again.

 

Any suggestions as to how to fix this?