Are you by any chance dual-citizen (Canadian/US) ? I had same problem when renewing Nexus for my wife (dual-citizen)
In this case, delete the Canadian passport info and retry.

Trying to contact them via email is a lesson in futility. Try calling them.

Yes I am dual - but do I need to go back to an enrollment center and get my Canadian passport put back in?

Did it work after you did the deletion?

Edited to add: It worked!! Thank you for the advice

More learnings as I am at 23 weeks
- USA says it can take "up to 6 months"
- they can only mail a card to a US / Canadian address
- Canadian side can only help so much. Sometimes you may need to call Blaine / someone in the US. Good times to call are during the first hour / last hour / lunch break of their office hours

Looking for guidance on renewing NEXUS for minors. I have a Login.gov account, do I need to set-up accounts for each of the kids in order to renew? Can I use my email address?

Thanks

Agreed, after my first application using my Canadian passport, CBP added three other passports I hold. I had issues trying to renew and was then told to delete any other passports from my profile before renewing.

You need a separate email address for each kid, but if you have a gmail address there are a couple of hacks.

You can change your gmail address by adding extra periods or a "+" symbol. If your email is "[email protected]" then you also own "myname+anything", "my.name", "my.na.me", "m.y.n.a.m.e", etc. You really own a huge number of different addresses. This can be handy.

For my Login.gov account, it's [email protected].

For my kid, I used [email protected].

The emails for that come to my account, but Login.gov accepts them as separate accounts. So it saves me maintaining a kid's email account.

Now, Aeroplan doesn't accept the + symbol, so I had to use an extra . in the name for him. So on Aeroplan, his address is [email protected]. I get the emails for both accounts but Aeroplan thinks they're separate.

You will need to set up Login.gov accounts for each kid, but you don't have to create email accounts for them.

For the phone number, you can use a single number for everyone in your family.

Applied for mother Mar 11.
Conditional Approval April 18.
Interview - Calais Maine April 23.

Only one month was totally unexpected .

This was for my wife (dual-citizen) She had to do the interview for renewal, so she brought the Canadian Passport at that time.
Not sure if you need to add that back ... that was in the section for "document for entry to US" or something?

Just got back from Canada from an interview for my son. Although his card is now expired, because we started the process before the expiration and perhaps because of the government shutdown, the Nexus people said he can still use his expired Nexus card until the replacement comes.

For NEXUS renewal

if you have conditional approval and need to attend interview, how soon do you get the new official card after you pass the interview? 1 week? 1 month?

(i know in the meanwhile you can use the old NEXUS card)

TTP cards typically take 5-8 business days to arrive.

Infant daughter's (Dual US/Canadian, Initial Application) Conditional Approval came this morning, April 25th. (I check daily). So it took about 10 weeks in total. Scheduled interview in Blaine, WA for April 29th.

Renewal application submitted January 15, 2019. Still pending conditional approval as of April 26 (13 weeks).

nexus renewal
 

I applied for a renewal 1 year before my nexus expires and I am still "pending review" It has been a little over a month. I've had nexus since it was called "Pace" years ago

Few more data points
 

3rd or 4th renewal

Applied late February
Approval 30 April
Card received ~10 May

New app (due to letting membership lapse - all info transferred from old GOES/GEOS account)
Applied ~7 March
Conditional Approval 7 May
No walk-ins available ~0850 9 May at YVR (12 people in line)
Will have to wait as getting to a Nexus place is a bit difficult where we are

FWIW, expired Nexus but using old KTN yielded Pre-Check for 3 flights out of 4 where the airline had a KTN input field (only one missing was a flight into the U.S. from Japan but not sure if that mattered, and one of the Pre Check was Canada into U.S. - might have speeded up processing at CBP preclearance)