Ammonia rash - stripping didn't fix?

Hi all, first time posting here so apologies if this is a common question but feeling so stuck.

We've been cloth diapering since 3 months or so and kiddo is now 2 and a few months. We use Nora's Nursery pockets and inserts, and Geffen Baby hemp inserts with a bamboo liner for nighttime. We've never had diaper rash issues but 6 weeks ago babe started having red irritation around the elastics. It was blotchy, raised, red and itchy. We started using Aquaphor over hydrocortisone and it slowly got better, but he would sill have a flare up now and then.

We've had a couple doctor appointments about it including a derm visit and both said it looked allergic, or possibly just like skin irritation from rubbing. We switched to disposables for two weeks and it got better very slowly. Went back to pockets and bam, it was back.

I read up on ammonia rash, which is definitely what it looks like, and diapers have a bit of an ammonia smell, so I stripped them per Fluff Love University--soaked everything including liners in 3 tbsp each borax, washing powder and calgon in a half tub of hot water, did a regular wash, bleach soak of liners only for 30 mins, then two more washes.

We've been using disposables the last three days with no issues. Put babe in a clean, stripped diaper last night and woke up to this dreaded rash back again.

We are headed to the doctor again but I am sure they will just tell us to go back to disposables. It's not a huge deal as we will be potty training soon anyways, but has anyone else had this problem before?? Is it a possible new allergy? This doesn't make sense to me as kiddo wears all cotton clothing. Any ideas on things we could try? We also have another on the way and this reaction makes me hesitant to use the same cloth diapers on a newborn.

Our washing routine is to spray out all diapers and liners with a bidet sprayer, do a quick wash with only diapers and cold water, then a full wash with enough other laundry to agitate well and extra rinse. We have an Electrolux front loading washer and use Tide powder detergent at the ratio recommended.

Thanks so much!