I understand you want to use the regular method on your Home office expenses, sryannucci. I'm here to share some insights on why the system reverts to the simplified one.
QuickBooks Self-Employed (QBSE) utilizes the simplified method to calculate your Federal estimated taxes and works as designed. Furthermore, it excludes the actual expenses from the calculation.
This default functionality of QBSE works to avoid double deductions. For additional reference on managing your Home office deductions, please check this article: Track home office deductions.
Also, I've added this article as your guide in organizing your transactions for an accurate Schedule C report: Schedule C and expense categories in QuickBooks Solopreneur and QuickBooks Self-Employed.
If you have more QuickBooks-related queries, don't hesitate to reply to this thread. We're always happy to help.