Notice of Correction - Electoral Roll Info

MaryNB

Transunion and Equifax didn't have my up-to-date electoral roll info (been on it at my current address since the end of 2018). I assume it's because the Royal Mail and Council use different addresses for my flat. It's a two-storey flat, Royal Mail refers to Basement Flat, Council refers to Ground Floor and Basement. 
Transunion corrected it immediately when I raised it in May. I submitted a request to Equifax in May, got an email on Saturday the 1st of August saying it had been corrected.

I applied for a DIP with Natwest this week and it was rejected due to an issue on my credit file (she couldn't see what it was).
I have £5 debt on my only credit card, use it every month but have never gone above 20% utilisation, never missed any credit payment on any account, never used my overdraft, never had a loan. I have a full-time job (never furloughed, no risk of redundancy), looking for a 70 LTV mortgage, no dependents.

I had a look at checkmyfile.com and the only things of note that appeared were the missing electoral roll data on Equifax and a notice of correction on Equifax from the 1st of June.
On clearscore (equifax), after I got the email about my electoral roll data they added 9 notes about upcoming changes on my August report. 6 notes involved removing and re-adding my accounts (credit card, current account, phone account), 2 related to adding and removing an NOC, 1 related to adding my electoral roll data. 

Checkmyfile says an NOC can affect credit applications. Transunion didn't add an NOC but Equifax did.
Did updating my electoral info really hit my credit file that bad? Is there anything I can do to remedy it? 

D3xt3r5L4b

Ask Equifax to remove the NOC. 

Simple.