Invoice TaxTotal is 0 even though being set otherwise

I’m saving 2 invoices that has transaction level tax.

I’m calculating the tax total based on the items amount field, setting the tax total amount of the record, and saving them.

Because they are set with transaction level tax, I’m also changing the “taxable” field under accounting, and setting each item to taxable = True, and setting the taxrate to 0%.

One of the invoices is being saved fine, the taxrate is still set to 0, and the taxtotal is set to the correct amount.

the other invoice doesn’t display the taxtotal, even though I’m using getvalue and log.debug right after the record.save operation to see what is the taxtotal, and I’m getting it fine.

note: I’m using dynamic record to save it.

Does anyone know what might be the difference between the correct invoice and the problematic one?