When a tax return is e-filed, the IRS accepts or rejects it within 48 hours. This is based only on a basic verification of identity and simple details (for example, that all the math adds up, that all required forms are included, that a dependent is not claimed by two different taxpayers, etc.). "Required forms" means, for example, that if you claim the child and dependent care credit on form 1040, you must also have form 2441. If you claim an energy credit, you must have included form 5695. And so on. Missing a schedule C is not necessarily going to be flagged as an error, because even if you had 1099-NEC income, or a schedule C last year, there could be reasons that you don't have a schedule C this year, so it would not be a reason for an administrative rejection. Acceptance is not an endorsement of your tax return or an agreement that it is correct, only that it passes basic quality control checks.
If you had a paid preparer who filed an incorrect tax return (was missing information) is should be their responsibility to correct the error. However, because of how the IRS workflow works, it is best to wait for the IRS to do something with the original return, before submitting an amended return. If the IRS has delayed your refund and is examining your return, they may come back with a letter asking for missing information. At that point, your preparer should write a letter explaining the mistake and enclosing a correct amended return.
Until the IRS makes some kind of decision or issues a letter or other activity, it is best to just wait.
Your preparer should be able to call the IRS on your behalf and ask about the delay (assuming this is a legitimate, IRS-registered tax preparer, and not someone who uses consumer software to file tax returns off the books and claim illegal fees).
