Unfortunately, reading others code is difficult because they
frequently use many methods I am unfamiliar with. I prefer a concise
explaination (pseudo code if you prefer) of the basic algorithm (such
as Dave's comments). ..However.

I suggested "collecting" the UnAnswered Q's by sorting _a_ list
in a sheet. I tried to point out that you don't have to sort the
actual list  that is used.
You can copy the list to another (possibly hidden) sheet  and (have
Excel) sort the copy for you.
I also suggested sorting the list, collecting the unanswered ones
(to another sheet), then "Un Sorting" back to the original order.
[This last may seem potentially distructive, thus less desirable].
Snippets below...

It appears that Dave is saving the unanswered questions  to another
sheet via an array. If I understand Dave's algo, he gathers all the
Q's in the array, then only saves the unanswered ones to the
"Missing-Ans-Sheet".
I think you could also collect ONLY the Unanawered Q's in the array
in the first place, then dump the entire array in the
"Missing-Ans-Sheet".

No?