I have a large worksheet that's using CONCAT to compile a list of email addresses. It was working fine, but I added some data that broke my list with some #N/A values. I cleaned those up, but ever since, CONCAT will either return a value of 0 or #VALUE! even though it used to work before.

I figured maybe I was exceeding the character limit of the cell, but even when switching it to CONCAT only 2 values, it errors out.

Here's the formula that I've been using that's worked until now:
Formula: copy to clipboard 
=CONCAT(INDIRECT("B5"&":B" &MATCH(LOOKUP(2,1/(B5:B7000<>""),B5:B7000),B5:B7000,0)+4))


The cell range (B5:B) is where the email addresses are stored. These aren't just raw data, they're the result of formulas. The formulas in B5:B are:
Formula: copy to clipboard 
=IFERROR(IF(INDEX($D$2:$D$11000,MATCH(EmailFeeder!E2,$C$2:$C$11000,0))="UNASSIGNED@SITE.COM; ","",INDEX($D$2:$D$11000,MATCH(EmailFeeder!E2,$C$2:$C$11000,0))),"")


I'm not sure why these formulas worked before but suddenly won't respond or return a value?

Any help would be appreciated!