The reason for the discrepancy is that the one-time withholding setting had a default "Reflection method" specified, which caused the document to generate incorrect postings. This is precisely what caused the amount not to be correctly included in the control statement.
How to fix it
Open the one-time withholding document that reflected the withholding of the accountable amount from the salary, and check the "Reflection method" field. Remove the default reflection method — leave this field empty (or set the correct value if required by your accounting policy). After that, re-post the document.
After removing the reflection method, the postings are generated correctly, and the withholding amount falls into place — the control statement matches.
Frequently asked questions
Why does the reflection method affect the postings? If a default reflection method is set in the document, the program may generate postings on accounts other than those needed for the correct reflection of the withholding, which distorts the final amounts in the reports.
Do I need to re-post all documents for the period after the fix? At a minimum, you need to re-post the one-time withholding document itself, and then check the payroll calculation for this period — re-posting it as well if necessary.