Top level header account incorrect balance

My top level expense header account has an amount which does not reflect the total of all expense accounts combined, it has a lower value than it should.

I closed my file for the 2024 financial year and as expected, the detailed expense account values zeroed, however ALL expense header account values have remained. I followed the process of changing a header account to detail then back again, and that worked to zero out the header accounts, except for the top level header account (because of course, I can't edit that account). Zeroing out the other header accounts also did not change the value in the top level header account.

Interestingly, when I closed the 2024 financial year, the top level expense header account became a negative value.

P.S yes I did backup my file just before I closed the 2024 financial year.

Many thanks