Include 0 value dates between min and max days - Continued

[#1]

I have already posted about this, but since my last post, for some reason the solution has stopped working.  A link to my first post is here:

Include 0 value dates between min and max days

So the problem I am having is that I want to show on my bar chart all days/year-months that have zero open sales orders so as to have a good visual timeline of when these orders will go out.  So the final expression that was derived from the first post is as follows:

sum ({$<SalesTransactionType = {'Open Order'}>}SalesTopLine)

+

sum ({$<OrderRequiredDateKey={">=$(=date(Min({<SalesTransactionType = {'Open Order'}>} OrderRequiredDateKey)))<=$(=date(Max({<SalesTransactionType = {'Open Order'}>} OrderRequiredDateKey)))"}>}0)

This works perfectly when I have not made any selections (see picture below with zero $ months):

But when I make a selection, it all goes away (see picture below, not zero $ months are showing):

Am I missing something? 

Thanks again.