Loan payment erroneously indicates paying balance in bulk; how to fix?

tale

I've got an offline loan entered into Quicken, that thankfully Quicken has absolutely no part in paying because it recently decided it was going to pay off the entire balance in full. I noticed because my future balance projections for my checking account had me deeply in the red.

I can't figure out to sort it all out, short of the drastic step of removing the account and adding it again, which I'm not sure how that impacts the 18 months of payments that already appear in my checking register.

For planning, I normally have Quicken enter all autopayments into my register automatically 90 days in advance. When I opened it today, the 1 April 2026 payment for the loan showed that it was paying the full balance. I immediately deleted that absurd transaction and set about figuring out how to have it put in the right value.

I went to the loan account, and reviewed the details for the loan, where it showed the current balance as the monthly payment amount. I used Edit Terms on the Loan Details tab and had it recalculate the monthly payment, for which it did calculate the correct value. Clicked Ok.

The MONTHLY PAYMENT in the header steadfastly stuck on what the balance would be as of March 2026.

I went back to Edit Terms. It still showed the correctly calculated value.

Then I went to Manage Bill & Income Reminders. The payment is shown as Done (despite NOT having the full balance payment in the register) with 0 left. It believes the Due Next On is 1 July 2031, the maturity date of the loan. I tried changing that to 1 April 2026 and editing the Amount Due — which was showing the March 2026 balance — but it will not let me change the values in the Split Transaction register to the actual principal and interest values.

Next I tried Validate on the whole file, which did not repair the issue. Strangely, one of two accounts it complained about that had "transaction(s) [that] were linked to account(s) no longer in Quicken", was this loan account, yet it was for split lines that didn't exist and were reported as 0.00 value. I checked all three of the transactions it flagged and could see nothing at all amiss with them.

Then I went back to Reminders and deleted the one for loan, and went back to the loan account. It still showed the correct payment in terms. Clicking OK with no changes changed nothing in the Monthly Payment header showing the balance as the payment, and the Projected Payoff graph still flatlines after March.

I tried to make trivial changes to Terms (eg, removing the final zero of a three decimal digit rate) but this did not cause any renewed attempt to set up payments.

Next I tried exiting and restarting Quicken. No material changes; Terms still show correct payment, header shows wrong payment and due date. Clicking Edit by the payment brings up the Loan Details window, and the Payment Options brings me to a window where I can pick setting up the loan payment reminder. I change the "Due Next On" to the 1 April date that is not currently in the register, and try to edit the amount due. As with my previous attempt to edit it in the Reminders screen, it does not allow me to edit the values, so still wants to post the entire remaining balance.

What I'm considering doing next is just creating a new parallel account for the loan, with the proper details and a Next Due On set to 1 April 2026. Then hiding this screwed up account, kept just to keep the history. I would rather have the existing account properly fixed though instead of hacking around it.

I have had this loan working just fine in Quicken for 18 months. Why has it gone insane now?

tale

Steps I have now taken:

1) Renamed the original account from Foo Loan to Foo Loan Borked, to preserve transaction history
2) Added a new Foo Loan with the loan details and Next Due on 1 Feb 2026.
3) Let the new account set up the automatic 90 day entry Reminder.
5) Restarted Quicken so the new reminders would post.
4) Deleted the future transactions for 1 Feb and 1 Mar that were already entered from the borked loan.
5) Entered a decrease of balance in the borked loan to zero it out as of today.
6) Went to the Account Details list for the borked account and hid it from the sidebar account list.

This does imply that if I ran any reports for the period from 1 June 2024 to 1 Jan 2026 it would show that I have double the debt from that loan, but that's highly unlikely to be a report I'd run.

Still really interested in knowing how the original problem materialized and how it could have been fixed without the second account.